Return null for all toCode enum params that are Enum.NULL (r4b)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Account.java

@@ -216,6 +216,8 @@ public class Account extends DomainResource {
     }
 
     public String toCode(AccountStatus code) {
+       if (code == AccountStatus.NULL)
+           return null;
        if (code == AccountStatus.ACTIVE)
         return "active";
       if (code == AccountStatus.INACTIVE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ActivityDefinition.java

@@ -400,6 +400,8 @@ public class ActivityDefinition extends CanonicalResource {
     }
 
     public String toCode(RequestResourceType code) {
+       if (code == RequestResourceType.NULL)
+           return null;
        if (code == RequestResourceType.APPOINTMENT)
         return "Appointment";
       if (code == RequestResourceType.APPOINTMENTRESPONSE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Address.java

@@ -180,6 +180,8 @@ public class Address extends DataType implements ICompositeType {
     }
 
     public String toCode(AddressType code) {
+       if (code == AddressType.NULL)
+           return null;
        if (code == AddressType.POSTAL)
         return "postal";
       if (code == AddressType.PHYSICAL)
@@ -358,6 +360,8 @@ public class Address extends DataType implements ICompositeType {
     }
 
     public String toCode(AddressUse code) {
+       if (code == AddressUse.NULL)
+           return null;
        if (code == AddressUse.HOME)
         return "home";
       if (code == AddressUse.WORK)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/AdverseEvent.java

@@ -164,6 +164,8 @@ public class AdverseEvent extends DomainResource {
     }
 
     public String toCode(AdverseEventActuality code) {
+       if (code == AdverseEventActuality.NULL)
+           return null;
        if (code == AdverseEventActuality.ACTUAL)
         return "actual";
       if (code == AdverseEventActuality.POTENTIAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/AllergyIntolerance.java

@@ -204,6 +204,8 @@ public class AllergyIntolerance extends DomainResource {
     }
 
     public String toCode(AllergyIntoleranceCategory code) {
+       if (code == AllergyIntoleranceCategory.NULL)
+           return null;
        if (code == AllergyIntoleranceCategory.FOOD)
         return "food";
       if (code == AllergyIntoleranceCategory.MEDICATION)
@@ -348,6 +350,8 @@ public class AllergyIntolerance extends DomainResource {
     }
 
     public String toCode(AllergyIntoleranceCriticality code) {
+       if (code == AllergyIntoleranceCriticality.NULL)
+           return null;
        if (code == AllergyIntoleranceCriticality.LOW)
         return "low";
       if (code == AllergyIntoleranceCriticality.HIGH)
@@ -488,6 +492,8 @@ public class AllergyIntolerance extends DomainResource {
     }
 
     public String toCode(AllergyIntoleranceSeverity code) {
+       if (code == AllergyIntoleranceSeverity.NULL)
+           return null;
        if (code == AllergyIntoleranceSeverity.MILD)
         return "mild";
       if (code == AllergyIntoleranceSeverity.MODERATE)
@@ -616,6 +622,8 @@ public class AllergyIntolerance extends DomainResource {
     }
 
     public String toCode(AllergyIntoleranceType code) {
+       if (code == AllergyIntoleranceType.NULL)
+           return null;
        if (code == AllergyIntoleranceType.ALLERGY)
         return "allergy";
       if (code == AllergyIntoleranceType.INTOLERANCE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Appointment.java

@@ -317,6 +317,8 @@ public class Appointment extends DomainResource {
     }
 
     public String toCode(AppointmentStatus code) {
+       if (code == AppointmentStatus.NULL)
+           return null;
        if (code == AppointmentStatus.PROPOSED)
         return "proposed";
       if (code == AppointmentStatus.PENDING)
@@ -473,6 +475,8 @@ public class Appointment extends DomainResource {
     }
 
     public String toCode(ParticipantRequired code) {
+       if (code == ParticipantRequired.NULL)
+           return null;
        if (code == ParticipantRequired.REQUIRED)
         return "required";
       if (code == ParticipantRequired.OPTIONAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/AuditEvent.java

@@ -217,6 +217,8 @@ public class AuditEvent extends DomainResource {
     }
 
     public String toCode(AuditEventAction code) {
+       if (code == AuditEventAction.NULL)
+           return null;
        if (code == AuditEventAction.C)
         return "C";
       if (code == AuditEventAction.R)
@@ -397,6 +399,8 @@ public class AuditEvent extends DomainResource {
     }
 
     public String toCode(AuditEventAgentNetworkType code) {
+       if (code == AuditEventAgentNetworkType.NULL)
+           return null;
        if (code == AuditEventAgentNetworkType._1)
         return "1";
       if (code == AuditEventAgentNetworkType._2)
@@ -562,6 +566,8 @@ public class AuditEvent extends DomainResource {
     }
 
     public String toCode(AuditEventOutcome code) {
+       if (code == AuditEventOutcome.NULL)
+           return null;
        if (code == AuditEventOutcome._0)
         return "0";
       if (code == AuditEventOutcome._4)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/BiologicallyDerivedProduct.java

@@ -224,6 +224,8 @@ public class BiologicallyDerivedProduct extends DomainResource {
     }
 
     public String toCode(BiologicallyDerivedProductCategory code) {
+       if (code == BiologicallyDerivedProductCategory.NULL)
+           return null;
        if (code == BiologicallyDerivedProductCategory.ORGAN)
         return "organ";
       if (code == BiologicallyDerivedProductCategory.TISSUE)
@@ -353,6 +355,8 @@ public class BiologicallyDerivedProduct extends DomainResource {
     }
 
     public String toCode(BiologicallyDerivedProductStatus code) {
+       if (code == BiologicallyDerivedProductStatus.NULL)
+           return null;
        if (code == BiologicallyDerivedProductStatus.AVAILABLE)
         return "available";
       if (code == BiologicallyDerivedProductStatus.UNAVAILABLE)
@@ -497,6 +501,8 @@ public class BiologicallyDerivedProduct extends DomainResource {
     }
 
     public String toCode(BiologicallyDerivedProductStorageScale code) {
+       if (code == BiologicallyDerivedProductStorageScale.NULL)
+           return null;
        if (code == BiologicallyDerivedProductStorageScale.FARENHEIT)
         return "farenheit";
       if (code == BiologicallyDerivedProductStorageScale.CELSIUS)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Bundle.java

@@ -296,6 +296,8 @@ public class Bundle extends Resource implements IBaseBundle {
     }
 
     public String toCode(BundleType code) {
+       if (code == BundleType.NULL)
+           return null;
        if (code == BundleType.DOCUMENT)
         return "document";
       if (code == BundleType.MESSAGE)
@@ -502,6 +504,8 @@ public class Bundle extends Resource implements IBaseBundle {
     }
 
     public String toCode(HTTPVerb code) {
+       if (code == HTTPVerb.NULL)
+           return null;
        if (code == HTTPVerb.GET)
         return "GET";
       if (code == HTTPVerb.HEAD)
@@ -650,6 +654,8 @@ public class Bundle extends Resource implements IBaseBundle {
     }
 
     public String toCode(SearchEntryMode code) {
+       if (code == SearchEntryMode.NULL)
+           return null;
        if (code == SearchEntryMode.MATCH)
         return "match";
       if (code == SearchEntryMode.INCLUDE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/CapabilityStatement.java

@@ -184,6 +184,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(ConditionalDeleteStatus code) {
+       if (code == ConditionalDeleteStatus.NULL)
+           return null;
        if (code == ConditionalDeleteStatus.NOTSUPPORTED)
         return "not-supported";
       if (code == ConditionalDeleteStatus.SINGLE)
@@ -344,6 +346,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(ConditionalReadStatus code) {
+       if (code == ConditionalReadStatus.NULL)
+           return null;
        if (code == ConditionalReadStatus.NOTSUPPORTED)
         return "not-supported";
       if (code == ConditionalReadStatus.MODIFIEDSINCE)
@@ -468,6 +472,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(DocumentMode code) {
+       if (code == DocumentMode.NULL)
+           return null;
        if (code == DocumentMode.PRODUCER)
         return "producer";
       if (code == DocumentMode.CONSUMER)
@@ -588,6 +594,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(EventCapabilityMode code) {
+       if (code == EventCapabilityMode.NULL)
+           return null;
        if (code == EventCapabilityMode.SENDER)
         return "sender";
       if (code == EventCapabilityMode.RECEIVER)
@@ -768,6 +776,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(ReferenceHandlingPolicy code) {
+       if (code == ReferenceHandlingPolicy.NULL)
+           return null;
        if (code == ReferenceHandlingPolicy.LITERAL)
         return "literal";
       if (code == ReferenceHandlingPolicy.LOGICAL)
@@ -913,6 +923,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(ResourceVersionPolicy code) {
+       if (code == ResourceVersionPolicy.NULL)
+           return null;
        if (code == ResourceVersionPolicy.NOVERSION)
         return "no-version";
       if (code == ResourceVersionPolicy.VERSIONED)
@@ -1035,6 +1047,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(RestfulCapabilityMode code) {
+       if (code == RestfulCapabilityMode.NULL)
+           return null;
        if (code == RestfulCapabilityMode.CLIENT)
         return "client";
       if (code == RestfulCapabilityMode.SERVER)
@@ -1191,6 +1205,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(SystemRestfulInteraction code) {
+       if (code == SystemRestfulInteraction.NULL)
+           return null;
        if (code == SystemRestfulInteraction.TRANSACTION)
         return "transaction";
       if (code == SystemRestfulInteraction.BATCH)
@@ -1441,6 +1457,8 @@ public class CapabilityStatement extends CanonicalResource implements IBaseConfo
     }
 
     public String toCode(TypeRestfulInteraction code) {
+       if (code == TypeRestfulInteraction.NULL)
+           return null;
        if (code == TypeRestfulInteraction.READ)
         return "read";
       if (code == TypeRestfulInteraction.VREAD)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/CarePlan.java

@@ -283,6 +283,8 @@ public class CarePlan extends DomainResource {
     }
 
     public String toCode(CarePlanActivityKind code) {
+       if (code == CarePlanActivityKind.NULL)
+           return null;
        if (code == CarePlanActivityKind.APPOINTMENT)
         return "Appointment";
       if (code == CarePlanActivityKind.COMMUNICATIONREQUEST)
@@ -545,6 +547,8 @@ public class CarePlan extends DomainResource {
     }
 
     public String toCode(CarePlanActivityStatus code) {
+       if (code == CarePlanActivityStatus.NULL)
+           return null;
        if (code == CarePlanActivityStatus.NOTSTARTED)
         return "not-started";
       if (code == CarePlanActivityStatus.SCHEDULED)
@@ -721,6 +725,8 @@ public class CarePlan extends DomainResource {
     }
 
     public String toCode(CarePlanIntent code) {
+       if (code == CarePlanIntent.NULL)
+           return null;
        if (code == CarePlanIntent.PROPOSAL)
         return "proposal";
       if (code == CarePlanIntent.PLAN)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/CareTeam.java

@@ -219,6 +219,8 @@ public class CareTeam extends DomainResource {
     }
 
     public String toCode(CareTeamStatus code) {
+       if (code == CareTeamStatus.NULL)
+           return null;
        if (code == CareTeamStatus.PROPOSED)
         return "proposed";
       if (code == CareTeamStatus.ACTIVE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/CatalogEntry.java

@@ -161,6 +161,8 @@ public class CatalogEntry extends DomainResource {
     }
 
     public String toCode(CatalogEntryRelationType code) {
+       if (code == CatalogEntryRelationType.NULL)
+           return null;
        if (code == CatalogEntryRelationType.TRIGGERS)
         return "triggers";
       if (code == CatalogEntryRelationType.ISREPLACEDBY)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ChargeItem.java

@@ -264,6 +264,8 @@ public class ChargeItem extends DomainResource {
     }
 
     public String toCode(ChargeItemStatus code) {
+       if (code == ChargeItemStatus.NULL)
+           return null;
        if (code == ChargeItemStatus.PLANNED)
         return "planned";
       if (code == ChargeItemStatus.BILLABLE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ClinicalImpression.java

@@ -186,6 +186,8 @@ public class ClinicalImpression extends DomainResource {
     }
 
     public String toCode(ClinicalImpressionStatus code) {
+       if (code == ClinicalImpressionStatus.NULL)
+           return null;
        if (code == ClinicalImpressionStatus.INPROGRESS)
         return "in-progress";
       if (code == ClinicalImpressionStatus.COMPLETED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ClinicalUseDefinition.java

@@ -215,6 +215,8 @@ public class ClinicalUseDefinition extends DomainResource {
     }
 
     public String toCode(ClinicalUseIssueType code) {
+       if (code == ClinicalUseIssueType.NULL)
+           return null;
        if (code == ClinicalUseIssueType.INDICATION)
         return "indication";
       if (code == ClinicalUseIssueType.CONTRAINDICATION)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/CodeSystem.java

@@ -225,6 +225,8 @@ public class CodeSystem extends CanonicalResource {
     }
 
     public String toCode(CodeSystemContentMode code) {
+       if (code == CodeSystemContentMode.NULL)
+           return null;
        if (code == CodeSystemContentMode.NOTPRESENT)
         return "not-present";
       if (code == CodeSystemContentMode.EXAMPLE)
@@ -398,6 +400,8 @@ public class CodeSystem extends CanonicalResource {
     }
 
     public String toCode(CodeSystemHierarchyMeaning code) {
+       if (code == CodeSystemHierarchyMeaning.NULL)
+           return null;
        if (code == CodeSystemHierarchyMeaning.GROUPEDBY)
         return "grouped-by";
       if (code == CodeSystemHierarchyMeaning.ISA)
@@ -615,6 +619,8 @@ public class CodeSystem extends CanonicalResource {
     }
 
     public String toCode(PropertyType code) {
+       if (code == PropertyType.NULL)
+           return null;
        if (code == PropertyType.CODE)
         return "code";
       if (code == PropertyType.CODING)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Composition.java

@@ -206,6 +206,8 @@ public class Composition extends DomainResource {
     }
 
     public String toCode(CompositionAttestationMode code) {
+       if (code == CompositionAttestationMode.NULL)
+           return null;
        if (code == CompositionAttestationMode.PERSONAL)
         return "personal";
       if (code == CompositionAttestationMode.PROFESSIONAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ConceptMap.java

@@ -322,6 +322,8 @@ public class ConceptMap extends CanonicalResource {
     }
 
     public String toCode(ConceptMapEquivalence code) {
+       if (code == ConceptMapEquivalence.NULL)
+           return null;
        if (code == ConceptMapEquivalence.RELATEDTO)
         return "relatedto";
       if (code == ConceptMapEquivalence.EQUIVALENT)
@@ -476,6 +478,8 @@ public class ConceptMap extends CanonicalResource {
     }
 
     public String toCode(ConceptMapGroupUnmappedMode code) {
+       if (code == ConceptMapGroupUnmappedMode.NULL)
+           return null;
        if (code == ConceptMapGroupUnmappedMode.PROVIDED)
         return "provided";
       if (code == ConceptMapGroupUnmappedMode.FIXED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Consent.java

@@ -200,6 +200,8 @@ public class Consent extends DomainResource {
     }
 
     public String toCode(ConsentDataMeaning code) {
+       if (code == ConsentDataMeaning.NULL)
+           return null;
        if (code == ConsentDataMeaning.INSTANCE)
         return "instance";
       if (code == ConsentDataMeaning.RELATED)
@@ -324,6 +326,8 @@ public class Consent extends DomainResource {
     }
 
     public String toCode(ConsentProvisionType code) {
+       if (code == ConsentProvisionType.NULL)
+           return null;
        if (code == ConsentProvisionType.DENY)
         return "deny";
       if (code == ConsentProvisionType.PERMIT)
@@ -518,6 +522,8 @@ public class Consent extends DomainResource {
     }
 
     public String toCode(ConsentState code) {
+       if (code == ConsentState.NULL)
+           return null;
        if (code == ConsentState.DRAFT)
         return "draft";
       if (code == ConsentState.PROPOSED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ContactPoint.java

@@ -261,6 +261,8 @@ public class ContactPoint extends DataType implements ICompositeType {
     }
 
     public String toCode(ContactPointSystem code) {
+       if (code == ContactPointSystem.NULL)
+           return null;
        if (code == ContactPointSystem.PHONE)
         return "phone";
       if (code == ContactPointSystem.FAX)
@@ -452,6 +454,8 @@ public class ContactPoint extends DataType implements ICompositeType {
     }
 
     public String toCode(ContactPointUse code) {
+       if (code == ContactPointUse.NULL)
+           return null;
        if (code == ContactPointUse.HOME)
         return "home";
       if (code == ContactPointUse.WORK)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Contract.java

@@ -469,6 +469,8 @@ public class Contract extends DomainResource {
     }
 
     public String toCode(ContractResourcePublicationStatusCodes code) {
+       if (code == ContractResourcePublicationStatusCodes.NULL)
+           return null;
        if (code == ContractResourcePublicationStatusCodes.AMENDED)
         return "amended";
       if (code == ContractResourcePublicationStatusCodes.APPENDED)
@@ -904,6 +906,8 @@ public class Contract extends DomainResource {
     }
 
     public String toCode(ContractResourceStatusCodes code) {
+       if (code == ContractResourceStatusCodes.NULL)
+           return null;
        if (code == ContractResourceStatusCodes.AMENDED)
         return "amended";
       if (code == ContractResourceStatusCodes.APPENDED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Contributor.java

@@ -195,6 +195,8 @@ public class Contributor extends DataType implements ICompositeType {
     }
 
     public String toCode(ContributorType code) {
+       if (code == ContributorType.NULL)
+           return null;
        if (code == ContributorType.AUTHOR)
         return "author";
       if (code == ContributorType.EDITOR)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/CoverageEligibilityRequest.java

@@ -204,6 +204,8 @@ public class CoverageEligibilityRequest extends DomainResource {
     }
 
     public String toCode(EligibilityRequestPurpose code) {
+       if (code == EligibilityRequestPurpose.NULL)
+           return null;
        if (code == EligibilityRequestPurpose.AUTHREQUIREMENTS)
         return "auth-requirements";
       if (code == EligibilityRequestPurpose.BENEFITS)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/CoverageEligibilityResponse.java

@@ -201,6 +201,8 @@ public class CoverageEligibilityResponse extends DomainResource {
     }
 
     public String toCode(EligibilityResponsePurpose code) {
+       if (code == EligibilityResponsePurpose.NULL)
+           return null;
        if (code == EligibilityResponsePurpose.AUTHREQUIREMENTS)
         return "auth-requirements";
       if (code == EligibilityResponsePurpose.BENEFITS)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/DataRequirement.java

@@ -160,6 +160,8 @@ public class DataRequirement extends DataType implements ICompositeType {
     }
 
     public String toCode(SortDirection code) {
+       if (code == SortDirection.NULL)
+           return null;
        if (code == SortDirection.ASCENDING)
         return "ascending";
       if (code == SortDirection.DESCENDING)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/DetectedIssue.java

@@ -184,6 +184,8 @@ public class DetectedIssue extends DomainResource {
     }
 
     public String toCode(DetectedIssueSeverity code) {
+       if (code == DetectedIssueSeverity.NULL)
+           return null;
        if (code == DetectedIssueSeverity.HIGH)
         return "high";
       if (code == DetectedIssueSeverity.MODERATE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Device.java

@@ -201,6 +201,8 @@ public class Device extends DomainResource {
     }
 
     public String toCode(FHIRDeviceStatus code) {
+       if (code == FHIRDeviceStatus.NULL)
+           return null;
        if (code == FHIRDeviceStatus.ACTIVE)
         return "active";
       if (code == FHIRDeviceStatus.INACTIVE)
@@ -400,6 +402,8 @@ public class Device extends DomainResource {
     }
 
     public String toCode(UDIEntryType code) {
+       if (code == UDIEntryType.NULL)
+           return null;
        if (code == UDIEntryType.BARCODE)
         return "barcode";
       if (code == UDIEntryType.RFID)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/DeviceMetric.java

@@ -198,6 +198,8 @@ public class DeviceMetric extends DomainResource {
     }
 
     public String toCode(DeviceMetricCalibrationState code) {
+       if (code == DeviceMetricCalibrationState.NULL)
+           return null;
        if (code == DeviceMetricCalibrationState.NOTCALIBRATED)
         return "not-calibrated";
       if (code == DeviceMetricCalibrationState.CALIBRATIONREQUIRED)
@@ -358,6 +360,8 @@ public class DeviceMetric extends DomainResource {
     }
 
     public String toCode(DeviceMetricCalibrationType code) {
+       if (code == DeviceMetricCalibrationType.NULL)
+           return null;
        if (code == DeviceMetricCalibrationType.UNSPECIFIED)
         return "unspecified";
       if (code == DeviceMetricCalibrationType.OFFSET)
@@ -519,6 +523,8 @@ public class DeviceMetric extends DomainResource {
     }
 
     public String toCode(DeviceMetricCategory code) {
+       if (code == DeviceMetricCategory.NULL)
+           return null;
        if (code == DeviceMetricCategory.MEASUREMENT)
         return "measurement";
       if (code == DeviceMetricCategory.SETTING)
@@ -751,6 +757,8 @@ public class DeviceMetric extends DomainResource {
     }
 
     public String toCode(DeviceMetricColor code) {
+       if (code == DeviceMetricColor.NULL)
+           return null;
        if (code == DeviceMetricColor.BLACK)
         return "black";
       if (code == DeviceMetricColor.RED)
@@ -919,6 +927,8 @@ public class DeviceMetric extends DomainResource {
     }
 
     public String toCode(DeviceMetricOperationalStatus code) {
+       if (code == DeviceMetricOperationalStatus.NULL)
+           return null;
        if (code == DeviceMetricOperationalStatus.ON)
         return "on";
       if (code == DeviceMetricOperationalStatus.OFF)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/DeviceUseStatement.java

@@ -235,6 +235,8 @@ public class DeviceUseStatement extends DomainResource {
     }
 
     public String toCode(DeviceUseStatementStatus code) {
+       if (code == DeviceUseStatementStatus.NULL)
+           return null;
        if (code == DeviceUseStatementStatus.ACTIVE)
         return "active";
       if (code == DeviceUseStatementStatus.COMPLETED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/DiagnosticReport.java

@@ -321,6 +321,8 @@ public class DiagnosticReport extends DomainResource {
     }
 
     public String toCode(DiagnosticReportStatus code) {
+       if (code == DiagnosticReportStatus.NULL)
+           return null;
        if (code == DiagnosticReportStatus.REGISTERED)
         return "registered";
       if (code == DiagnosticReportStatus.PARTIAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ElementDefinition.java

@@ -186,6 +186,8 @@ public class ElementDefinition extends BackboneType implements ICompositeType {
     }
 
     public String toCode(AggregationMode code) {
+       if (code == AggregationMode.NULL)
+           return null;
        if (code == AggregationMode.CONTAINED)
         return "contained";
       if (code == AggregationMode.REFERENCED)
@@ -309,6 +311,8 @@ public class ElementDefinition extends BackboneType implements ICompositeType {
     }
 
     public String toCode(ConstraintSeverity code) {
+       if (code == ConstraintSeverity.NULL)
+           return null;
        if (code == ConstraintSeverity.ERROR)
         return "error";
       if (code == ConstraintSeverity.WARNING)
@@ -488,6 +492,8 @@ public class ElementDefinition extends BackboneType implements ICompositeType {
     }
 
     public String toCode(DiscriminatorType code) {
+       if (code == DiscriminatorType.NULL)
+           return null;
        if (code == DiscriminatorType.VALUE)
         return "value";
       if (code == DiscriminatorType.EXISTS)
@@ -668,6 +674,8 @@ public class ElementDefinition extends BackboneType implements ICompositeType {
     }
 
     public String toCode(PropertyRepresentation code) {
+       if (code == PropertyRepresentation.NULL)
+           return null;
        if (code == PropertyRepresentation.XMLATTR)
         return "xmlAttr";
       if (code == PropertyRepresentation.XMLTEXT)
@@ -812,6 +820,8 @@ public class ElementDefinition extends BackboneType implements ICompositeType {
     }
 
     public String toCode(ReferenceVersionRules code) {
+       if (code == ReferenceVersionRules.NULL)
+           return null;
        if (code == ReferenceVersionRules.EITHER)
         return "either";
       if (code == ReferenceVersionRules.INDEPENDENT)
@@ -955,6 +965,8 @@ public class ElementDefinition extends BackboneType implements ICompositeType {
     }
 
     public String toCode(SlicingRules code) {
+       if (code == SlicingRules.NULL)
+           return null;
        if (code == SlicingRules.CLOSED)
         return "closed";
       if (code == SlicingRules.OPEN)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Encounter.java

@@ -202,6 +202,8 @@ public class Encounter extends DomainResource {
     }
 
     public String toCode(EncounterLocationStatus code) {
+       if (code == EncounterLocationStatus.NULL)
+           return null;
        if (code == EncounterLocationStatus.PLANNED)
         return "planned";
       if (code == EncounterLocationStatus.ACTIVE)
@@ -457,6 +459,8 @@ public class Encounter extends DomainResource {
     }
 
     public String toCode(EncounterStatus code) {
+       if (code == EncounterStatus.NULL)
+           return null;
        if (code == EncounterStatus.PLANNED)
         return "planned";
       if (code == EncounterStatus.ARRIVED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Endpoint.java

@@ -236,6 +236,8 @@ public class Endpoint extends DomainResource {
     }
 
     public String toCode(EndpointStatus code) {
+       if (code == EndpointStatus.NULL)
+           return null;
        if (code == EndpointStatus.ACTIVE)
         return "active";
       if (code == EndpointStatus.SUSPENDED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Enumerations.java

@@ -185,6 +185,8 @@ public class Enumerations {
     }
 
     public String toCode(ActionCardinalityBehavior code) {
+       if (code == ActionCardinalityBehavior.NULL)
+           return null;
        if (code == ActionCardinalityBehavior.SINGLE)
         return "single";
       if (code == ActionCardinalityBehavior.MULTIPLE)
@@ -320,6 +322,8 @@ public class Enumerations {
     }
 
     public String toCode(ActionConditionKind code) {
+       if (code == ActionConditionKind.NULL)
+           return null;
        if (code == ActionConditionKind.APPLICABILITY)
         return "applicability";
       if (code == ActionConditionKind.START)
@@ -468,6 +472,8 @@ public class Enumerations {
     }
 
     public String toCode(ActionGroupingBehavior code) {
+       if (code == ActionGroupingBehavior.NULL)
+           return null;
        if (code == ActionGroupingBehavior.VISUALGROUP)
         return "visual-group";
       if (code == ActionGroupingBehavior.LOGICALGROUP)
@@ -623,6 +629,8 @@ public class Enumerations {
     }
 
     public String toCode(ActionParticipantType code) {
+       if (code == ActionParticipantType.NULL)
+           return null;
        if (code == ActionParticipantType.PATIENT)
         return "patient";
       if (code == ActionParticipantType.PRACTITIONER)
@@ -750,6 +758,8 @@ public class Enumerations {
     }
 
     public String toCode(ActionPrecheckBehavior code) {
+       if (code == ActionPrecheckBehavior.NULL)
+           return null;
        if (code == ActionPrecheckBehavior.YES)
         return "yes";
       if (code == ActionPrecheckBehavior.NO)
@@ -993,6 +1003,8 @@ public class Enumerations {
     }
 
     public String toCode(ActionRelationshipType code) {
+       if (code == ActionRelationshipType.NULL)
+           return null;
        if (code == ActionRelationshipType.BEFORESTART)
         return "before-start";
       if (code == ActionRelationshipType.BEFORE)
@@ -1146,6 +1158,8 @@ public class Enumerations {
     }
 
     public String toCode(ActionRequiredBehavior code) {
+       if (code == ActionRequiredBehavior.NULL)
+           return null;
        if (code == ActionRequiredBehavior.MUST)
         return "must";
       if (code == ActionRequiredBehavior.COULD)
@@ -1339,6 +1353,8 @@ public class Enumerations {
     }
 
     public String toCode(ActionSelectionBehavior code) {
+       if (code == ActionSelectionBehavior.NULL)
+           return null;
        if (code == ActionSelectionBehavior.ANY)
         return "any";
       if (code == ActionSelectionBehavior.ALL)
@@ -1500,6 +1516,8 @@ public class Enumerations {
     }
 
     public String toCode(AdministrativeGender code) {
+       if (code == AdministrativeGender.NULL)
+           return null;
        if (code == AdministrativeGender.MALE)
         return "male";
       if (code == AdministrativeGender.FEMALE)
@@ -1666,6 +1684,8 @@ public class Enumerations {
     }
 
     public String toCode(BindingStrength code) {
+       if (code == BindingStrength.NULL)
+           return null;
        if (code == BindingStrength.REQUIRED)
         return "required";
       if (code == BindingStrength.EXTENSIBLE)
@@ -1810,6 +1830,8 @@ public class Enumerations {
     }
 
     public String toCode(CapabilityStatementKind code) {
+       if (code == CapabilityStatementKind.NULL)
+           return null;
        if (code == CapabilityStatementKind.INSTANCE)
         return "instance";
       if (code == CapabilityStatementKind.CAPABILITY)
@@ -1983,6 +2005,8 @@ public class Enumerations {
     }
 
     public String toCode(CompartmentType code) {
+       if (code == CompartmentType.NULL)
+           return null;
        if (code == CompartmentType.PATIENT)
         return "Patient";
       if (code == CompartmentType.ENCOUNTER)
@@ -2149,6 +2173,8 @@ public class Enumerations {
     }
 
     public String toCode(CompositionStatus code) {
+       if (code == CompositionStatus.NULL)
+           return null;
        if (code == CompositionStatus.PRELIMINARY)
         return "preliminary";
       if (code == CompositionStatus.FINAL)
@@ -2360,6 +2386,8 @@ public class Enumerations {
     }
 
     public String toCode(DaysOfWeek code) {
+       if (code == DaysOfWeek.NULL)
+           return null;
        if (code == DaysOfWeek.MON)
         return "mon";
       if (code == DaysOfWeek.TUE)
@@ -2559,6 +2587,8 @@ public class Enumerations {
     }
 
     public String toCode(DeviceNameType code) {
+       if (code == DeviceNameType.NULL)
+           return null;
        if (code == DeviceNameType.UDILABELNAME)
         return "udi-label-name";
       if (code == DeviceNameType.USERFRIENDLYNAME)
@@ -2702,6 +2732,8 @@ public class Enumerations {
     }
 
     public String toCode(DocumentReferenceStatus code) {
+       if (code == DocumentReferenceStatus.NULL)
+           return null;
        if (code == DocumentReferenceStatus.CURRENT)
         return "current";
       if (code == DocumentReferenceStatus.SUPERSEDED)
@@ -2858,6 +2890,8 @@ public class Enumerations {
     }
 
     public String toCode(DocumentRelationshipType code) {
+       if (code == DocumentRelationshipType.NULL)
+           return null;
        if (code == DocumentRelationshipType.REPLACES)
         return "replaces";
       if (code == DocumentRelationshipType.TRANSFORMS)
@@ -3099,6 +3133,8 @@ public class Enumerations {
     }
 
     public String toCode(EventStatus code) {
+       if (code == EventStatus.NULL)
+           return null;
        if (code == EventStatus.PREPARATION)
         return "preparation";
       if (code == EventStatus.INPROGRESS)
@@ -3273,6 +3309,8 @@ public class Enumerations {
     }
 
     public String toCode(EvidenceVariableHandling code) {
+       if (code == EvidenceVariableHandling.NULL)
+           return null;
        if (code == EvidenceVariableHandling.CONTINUOUS)
         return "continuous";
       if (code == EvidenceVariableHandling.DICHOTOMOUS)
@@ -7457,6 +7495,8 @@ public class Enumerations {
     }
 
     public String toCode(FHIRAllTypes code) {
+       if (code == FHIRAllTypes.NULL)
+           return null;
        if (code == FHIRAllTypes.ADDRESS)
         return "Address";
       if (code == FHIRAllTypes.AGE)
@@ -9048,6 +9088,8 @@ public class Enumerations {
     }
 
     public String toCode(FHIRVersion code) {
+       if (code == FHIRVersion.NULL)
+           return null;
        if (code == FHIRVersion._0_01)
         return "0.01";
       if (code == FHIRVersion._0_05)
@@ -9409,6 +9451,8 @@ public class Enumerations {
     }
 
     public String toCode(FilterOperator code) {
+       if (code == FilterOperator.NULL)
+           return null;
        if (code == FilterOperator.EQUAL)
         return "=";
       if (code == FilterOperator.ISA)
@@ -9576,6 +9620,8 @@ public class Enumerations {
     }
 
     public String toCode(FinancialResourceStatusCodes code) {
+       if (code == FinancialResourceStatusCodes.NULL)
+           return null;
        if (code == FinancialResourceStatusCodes.ACTIVE)
         return "active";
       if (code == FinancialResourceStatusCodes.CANCELLED)
@@ -9769,6 +9815,8 @@ public class Enumerations {
     }
 
     public String toCode(GroupMeasure code) {
+       if (code == GroupMeasure.NULL)
+           return null;
        if (code == GroupMeasure.MEAN)
         return "mean";
       if (code == GroupMeasure.MEDIAN)
@@ -9968,6 +10016,8 @@ public class Enumerations {
     }
 
     public String toCode(InvoicePriceComponentType code) {
+       if (code == InvoicePriceComponentType.NULL)
+           return null;
        if (code == InvoicePriceComponentType.BASE)
         return "base";
       if (code == InvoicePriceComponentType.SURCHARGE)
@@ -10114,6 +10164,8 @@ public class Enumerations {
     }
 
     public String toCode(ListMode code) {
+       if (code == ListMode.NULL)
+           return null;
        if (code == ListMode.WORKING)
         return "working";
       if (code == ListMode.SNAPSHOT)
@@ -10235,6 +10287,8 @@ public class Enumerations {
     }
 
     public String toCode(MeasureImprovementNotation code) {
+       if (code == MeasureImprovementNotation.NULL)
+           return null;
        if (code == MeasureImprovementNotation.INCREASE)
         return "increase";
       if (code == MeasureImprovementNotation.DECREASE)
@@ -10316,6 +10370,8 @@ public class Enumerations {
     }
 
     public String toCode(MimeTypes code) {
+       if (code == MimeTypes.NULL)
+           return null;
        return "?";
    }
 
@@ -10447,6 +10503,8 @@ public class Enumerations {
     }
 
     public String toCode(NoteType code) {
+       if (code == NoteType.NULL)
+           return null;
        if (code == NoteType.DISPLAY)
         return "display";
       if (code == NoteType.PRINT)
@@ -10690,6 +10748,8 @@ public class Enumerations {
     }
 
     public String toCode(ObservationStatus code) {
+       if (code == ObservationStatus.NULL)
+           return null;
        if (code == ObservationStatus.REGISTERED)
         return "registered";
       if (code == ObservationStatus.PRELIMINARY)
@@ -10819,6 +10879,8 @@ public class Enumerations {
     }
 
     public String toCode(OperationParameterUse code) {
+       if (code == OperationParameterUse.NULL)
+           return null;
        if (code == OperationParameterUse.IN)
         return "in";
       if (code == OperationParameterUse.OUT)
@@ -10976,6 +11038,8 @@ public class Enumerations {
     }
 
     public String toCode(ParticipationStatus code) {
+       if (code == ParticipationStatus.NULL)
+           return null;
        if (code == ParticipationStatus.ACCEPTED)
         return "accepted";
       if (code == ParticipationStatus.DECLINED)
@@ -11137,6 +11201,8 @@ public class Enumerations {
     }
 
     public String toCode(PublicationStatus code) {
+       if (code == PublicationStatus.NULL)
+           return null;
        if (code == PublicationStatus.DRAFT)
         return "draft";
       if (code == PublicationStatus.ACTIVE)
@@ -11294,6 +11360,8 @@ public class Enumerations {
     }
 
     public String toCode(QuantityComparator code) {
+       if (code == QuantityComparator.NULL)
+           return null;
        if (code == QuantityComparator.LESS_THAN)
         return "<";
       if (code == QuantityComparator.LESS_OR_EQUAL)
@@ -11452,6 +11520,8 @@ public class Enumerations {
     }
 
     public String toCode(RemittanceOutcome code) {
+       if (code == RemittanceOutcome.NULL)
+           return null;
        if (code == RemittanceOutcome.QUEUED)
         return "queued";
       if (code == RemittanceOutcome.COMPLETE)
@@ -11712,6 +11782,8 @@ public class Enumerations {
     }
 
     public String toCode(RequestIntent code) {
+       if (code == RequestIntent.NULL)
+           return null;
        if (code == RequestIntent.PROPOSAL)
         return "proposal";
       if (code == RequestIntent.PLAN)
@@ -11881,6 +11953,8 @@ public class Enumerations {
     }
 
     public String toCode(RequestPriority code) {
+       if (code == RequestPriority.NULL)
+           return null;
        if (code == RequestPriority.ROUTINE)
         return "routine";
       if (code == RequestPriority.URGENT)
@@ -12102,6 +12176,8 @@ public class Enumerations {
     }
 
     public String toCode(RequestStatus code) {
+       if (code == RequestStatus.NULL)
+           return null;
        if (code == RequestStatus.DRAFT)
         return "draft";
       if (code == RequestStatus.ACTIVE)
@@ -15031,6 +15107,8 @@ public class Enumerations {
     }
 
     public String toCode(ResourceTypeEnum code) {
+       if (code == ResourceTypeEnum.NULL)
+           return null;
        if (code == ResourceTypeEnum.RESOURCE)
         return "Resource";
       if (code == ResourceTypeEnum.BINARY)
@@ -15563,6 +15641,8 @@ public class Enumerations {
     }
 
     public String toCode(SearchParamType code) {
+       if (code == SearchParamType.NULL)
+           return null;
        if (code == SearchParamType.NUMBER)
         return "number";
       if (code == SearchParamType.DATE)
@@ -15731,6 +15811,8 @@ public class Enumerations {
     }
 
     public String toCode(SubscriptionStatus code) {
+       if (code == SubscriptionStatus.NULL)
+           return null;
        if (code == SubscriptionStatus.REQUESTED)
         return "requested";
       if (code == SubscriptionStatus.ACTIVE)
@@ -15872,6 +15954,8 @@ public class Enumerations {
     }
 
     public String toCode(Use code) {
+       if (code == Use.NULL)
+           return null;
        if (code == Use.CLAIM)
         return "claim";
       if (code == Use.PREAUTHORIZATION)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/EpisodeOfCare.java

@@ -263,6 +263,8 @@ public class EpisodeOfCare extends DomainResource {
     }
 
     public String toCode(EpisodeOfCareStatus code) {
+       if (code == EpisodeOfCareStatus.NULL)
+           return null;
        if (code == EpisodeOfCareStatus.PLANNED)
         return "planned";
       if (code == EpisodeOfCareStatus.WAITLIST)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/EvidenceReport.java

@@ -272,6 +272,8 @@ public class EvidenceReport extends DomainResource {
     }
 
     public String toCode(ReportRelationshipType code) {
+       if (code == ReportRelationshipType.NULL)
+           return null;
        if (code == ReportRelationshipType.REPLACES)
         return "replaces";
       if (code == ReportRelationshipType.AMENDS)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/EvidenceVariable.java

@@ -161,6 +161,8 @@ public class EvidenceVariable extends DomainResource {
     }
 
     public String toCode(CharacteristicCombination code) {
+       if (code == CharacteristicCombination.NULL)
+           return null;
        if (code == CharacteristicCombination.INTERSECTION)
         return "intersection";
       if (code == CharacteristicCombination.UNION)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ExampleScenario.java

@@ -160,6 +160,8 @@ public class ExampleScenario extends CanonicalResource {
     }
 
     public String toCode(ExampleScenarioActorType code) {
+       if (code == ExampleScenarioActorType.NULL)
+           return null;
        if (code == ExampleScenarioActorType.PERSON)
         return "person";
       if (code == ExampleScenarioActorType.ENTITY)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ExplanationOfBenefit.java

@@ -199,6 +199,8 @@ public class ExplanationOfBenefit extends DomainResource {
     }
 
     public String toCode(ExplanationOfBenefitStatus code) {
+       if (code == ExplanationOfBenefitStatus.NULL)
+           return null;
        if (code == ExplanationOfBenefitStatus.ACTIVE)
         return "active";
       if (code == ExplanationOfBenefitStatus.CANCELLED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/FamilyMemberHistory.java

@@ -199,6 +199,8 @@ public class FamilyMemberHistory extends DomainResource {
     }
 
     public String toCode(FamilyHistoryStatus code) {
+       if (code == FamilyHistoryStatus.NULL)
+           return null;
        if (code == FamilyHistoryStatus.PARTIAL)
         return "partial";
       if (code == FamilyHistoryStatus.COMPLETED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Flag.java

@@ -179,6 +179,8 @@ public class Flag extends DomainResource {
     }
 
     public String toCode(FlagStatus code) {
+       if (code == FlagStatus.NULL)
+           return null;
        if (code == FlagStatus.ACTIVE)
         return "active";
       if (code == FlagStatus.INACTIVE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Goal.java

@@ -290,6 +290,8 @@ public class Goal extends DomainResource {
     }
 
     public String toCode(GoalLifecycleStatus code) {
+       if (code == GoalLifecycleStatus.NULL)
+           return null;
        if (code == GoalLifecycleStatus.PROPOSED)
         return "proposed";
       if (code == GoalLifecycleStatus.PLANNED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/GraphDefinition.java

@@ -199,6 +199,8 @@ public class GraphDefinition extends CanonicalResource {
     }
 
     public String toCode(GraphCompartmentRule code) {
+       if (code == GraphCompartmentRule.NULL)
+           return null;
        if (code == GraphCompartmentRule.IDENTICAL)
         return "identical";
       if (code == GraphCompartmentRule.MATCHING)
@@ -324,6 +326,8 @@ public class GraphDefinition extends CanonicalResource {
     }
 
     public String toCode(GraphCompartmentUse code) {
+       if (code == GraphCompartmentUse.NULL)
+           return null;
        if (code == GraphCompartmentUse.CONDITION)
         return "condition";
       if (code == GraphCompartmentUse.REQUIREMENT)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Group.java

@@ -236,6 +236,8 @@ public class Group extends DomainResource {
     }
 
     public String toCode(GroupType code) {
+       if (code == GroupType.NULL)
+           return null;
        if (code == GroupType.PERSON)
         return "person";
       if (code == GroupType.ANIMAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/GuidanceResponse.java

@@ -236,6 +236,8 @@ public class GuidanceResponse extends DomainResource {
     }
 
     public String toCode(GuidanceResponseStatus code) {
+       if (code == GuidanceResponseStatus.NULL)
+           return null;
        if (code == GuidanceResponseStatus.SUCCESS)
         return "success";
       if (code == GuidanceResponseStatus.DATAREQUESTED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/HumanName.java

@@ -262,6 +262,8 @@ public class HumanName extends DataType implements ICompositeType {
     }
 
     public String toCode(NameUse code) {
+       if (code == NameUse.NULL)
+           return null;
        if (code == NameUse.USUAL)
         return "usual";
       if (code == NameUse.OFFICIAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Identifier.java

@@ -220,6 +220,8 @@ public class Identifier extends DataType implements ICompositeType {
     }
 
     public String toCode(IdentifierUse code) {
+       if (code == IdentifierUse.NULL)
+           return null;
        if (code == IdentifierUse.USUAL)
         return "usual";
       if (code == IdentifierUse.OFFICIAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ImagingStudy.java

@@ -225,6 +225,8 @@ public class ImagingStudy extends DomainResource {
     }
 
     public String toCode(ImagingStudyStatus code) {
+       if (code == ImagingStudyStatus.NULL)
+           return null;
        if (code == ImagingStudyStatus.REGISTERED)
         return "registered";
       if (code == ImagingStudyStatus.AVAILABLE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Immunization.java

@@ -183,6 +183,8 @@ public class Immunization extends DomainResource {
     }
 
     public String toCode(ImmunizationStatusCodes code) {
+       if (code == ImmunizationStatusCodes.NULL)
+           return null;
        if (code == ImmunizationStatusCodes.COMPLETED)
         return "completed";
       if (code == ImmunizationStatusCodes.ENTEREDINERROR)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ImmunizationEvaluation.java

@@ -165,6 +165,8 @@ public class ImmunizationEvaluation extends DomainResource {
     }
 
     public String toCode(ImmunizationEvaluationStatusCodes code) {
+       if (code == ImmunizationEvaluationStatusCodes.NULL)
+           return null;
        if (code == ImmunizationEvaluationStatusCodes.COMPLETED)
         return "completed";
       if (code == ImmunizationEvaluationStatusCodes.ENTEREDINERROR)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ImplementationGuide.java

@@ -204,6 +204,8 @@ public class ImplementationGuide extends CanonicalResource {
     }
 
     public String toCode(GuidePageGeneration code) {
+       if (code == GuidePageGeneration.NULL)
+           return null;
        if (code == GuidePageGeneration.HTML)
         return "html";
       if (code == GuidePageGeneration.MARKDOWN)
@@ -494,6 +496,8 @@ public class ImplementationGuide extends CanonicalResource {
     }
 
     public String toCode(GuideParameterCode code) {
+       if (code == GuideParameterCode.NULL)
+           return null;
        if (code == GuideParameterCode.APPLY)
         return "apply";
       if (code == GuideParameterCode.PATHRESOURCE)
@@ -10722,6 +10726,8 @@ public class ImplementationGuide extends CanonicalResource {
     }
 
     public String toCode(SPDXLicense code) {
+       if (code == SPDXLicense.NULL)
+           return null;
        if (code == SPDXLicense._0BSD)
         return "0BSD";
       if (code == SPDXLicense.AAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Invoice.java

@@ -216,6 +216,8 @@ public class Invoice extends DomainResource {
     }
 
     public String toCode(InvoiceStatus code) {
+       if (code == InvoiceStatus.NULL)
+           return null;
        if (code == InvoiceStatus.DRAFT)
         return "draft";
       if (code == InvoiceStatus.ISSUED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Linkage.java

@@ -183,6 +183,8 @@ public class Linkage extends DomainResource {
     }
 
     public String toCode(LinkageType code) {
+       if (code == LinkageType.NULL)
+           return null;
        if (code == LinkageType.SOURCE)
         return "source";
       if (code == LinkageType.ALTERNATE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ListResource.java

@@ -178,6 +178,8 @@ public class ListResource extends DomainResource {
     }
 
     public String toCode(ListStatus code) {
+       if (code == ListStatus.NULL)
+           return null;
        if (code == ListStatus.CURRENT)
         return "current";
       if (code == ListStatus.RETIRED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Location.java

@@ -166,6 +166,8 @@ public class Location extends DomainResource {
     }
 
     public String toCode(LocationMode code) {
+       if (code == LocationMode.NULL)
+           return null;
        if (code == LocationMode.INSTANCE)
         return "instance";
       if (code == LocationMode.KIND)
@@ -304,6 +306,8 @@ public class Location extends DomainResource {
     }
 
     public String toCode(LocationStatus code) {
+       if (code == LocationStatus.NULL)
+           return null;
        if (code == LocationStatus.ACTIVE)
         return "active";
       if (code == LocationStatus.SUSPENDED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MeasureReport.java

@@ -180,6 +180,8 @@ public class MeasureReport extends DomainResource {
     }
 
     public String toCode(MeasureReportStatus code) {
+       if (code == MeasureReportStatus.NULL)
+           return null;
        if (code == MeasureReportStatus.COMPLETE)
         return "complete";
       if (code == MeasureReportStatus.PENDING)
@@ -341,6 +343,8 @@ public class MeasureReport extends DomainResource {
     }
 
     public String toCode(MeasureReportType code) {
+       if (code == MeasureReportType.NULL)
+           return null;
        if (code == MeasureReportType.INDIVIDUAL)
         return "individual";
       if (code == MeasureReportType.SUBJECTLIST)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Medication.java

@@ -180,6 +180,8 @@ public class Medication extends DomainResource {
     }
 
     public String toCode(MedicationStatusCodes code) {
+       if (code == MedicationStatusCodes.NULL)
+           return null;
        if (code == MedicationStatusCodes.ACTIVE)
         return "active";
       if (code == MedicationStatusCodes.INACTIVE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MedicationAdministration.java

@@ -270,6 +270,8 @@ public class MedicationAdministration extends DomainResource {
     }
 
     public String toCode(MedicationAdministrationStatusCodes code) {
+       if (code == MedicationAdministrationStatusCodes.NULL)
+           return null;
        if (code == MedicationAdministrationStatusCodes.INPROGRESS)
         return "in-progress";
       if (code == MedicationAdministrationStatusCodes.NOTDONE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MedicationDispense.java

@@ -298,6 +298,8 @@ public class MedicationDispense extends DomainResource {
     }
 
     public String toCode(MedicationDispenseStatusCodes code) {
+       if (code == MedicationDispenseStatusCodes.NULL)
+           return null;
        if (code == MedicationDispenseStatusCodes.PREPARATION)
         return "preparation";
       if (code == MedicationDispenseStatusCodes.INPROGRESS)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MedicationKnowledge.java

@@ -179,6 +179,8 @@ public class MedicationKnowledge extends DomainResource {
     }
 
     public String toCode(MedicationKnowledgeStatusCodes code) {
+       if (code == MedicationKnowledgeStatusCodes.NULL)
+           return null;
        if (code == MedicationKnowledgeStatusCodes.ACTIVE)
         return "active";
       if (code == MedicationKnowledgeStatusCodes.INACTIVE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MedicationRequest.java

@@ -281,6 +281,8 @@ public class MedicationRequest extends DomainResource {
     }
 
     public String toCode(MedicationRequestIntent code) {
+       if (code == MedicationRequestIntent.NULL)
+           return null;
        if (code == MedicationRequestIntent.PROPOSAL)
         return "proposal";
       if (code == MedicationRequestIntent.PLAN)
@@ -533,6 +535,8 @@ public class MedicationRequest extends DomainResource {
     }
 
     public String toCode(MedicationrequestStatus code) {
+       if (code == MedicationrequestStatus.NULL)
+           return null;
        if (code == MedicationrequestStatus.ACTIVE)
         return "active";
       if (code == MedicationrequestStatus.ONHOLD)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MedicationStatement.java

@@ -294,6 +294,8 @@ public class MedicationStatement extends DomainResource {
     }
 
     public String toCode(MedicationStatusCodes code) {
+       if (code == MedicationStatusCodes.NULL)
+           return null;
        if (code == MedicationStatusCodes.ACTIVE)
         return "active";
       if (code == MedicationStatusCodes.COMPLETED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MessageDefinition.java

@@ -184,6 +184,8 @@ public class MessageDefinition extends CanonicalResource {
     }
 
     public String toCode(MessageSignificanceCategory code) {
+       if (code == MessageSignificanceCategory.NULL)
+           return null;
        if (code == MessageSignificanceCategory.CONSEQUENCE)
         return "consequence";
       if (code == MessageSignificanceCategory.CURRENCY)
@@ -342,6 +344,8 @@ public class MessageDefinition extends CanonicalResource {
     }
 
     public String toCode(MessageheaderResponseRequest code) {
+       if (code == MessageheaderResponseRequest.NULL)
+           return null;
        if (code == MessageheaderResponseRequest.ALWAYS)
         return "always";
       if (code == MessageheaderResponseRequest.ONERROR)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MessageHeader.java

@@ -186,6 +186,8 @@ public class MessageHeader extends DomainResource {
     }
 
     public String toCode(ResponseType code) {
+       if (code == ResponseType.NULL)
+           return null;
        if (code == ResponseType.OK)
         return "ok";
       if (code == ResponseType.TRANSIENTERROR)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/MolecularSequence.java

@@ -161,6 +161,8 @@ public class MolecularSequence extends DomainResource {
     }
 
     public String toCode(OrientationType code) {
+       if (code == OrientationType.NULL)
+           return null;
        if (code == OrientationType.SENSE)
         return "sense";
       if (code == OrientationType.ANTISENSE)
@@ -299,6 +301,8 @@ public class MolecularSequence extends DomainResource {
     }
 
     public String toCode(QualityType code) {
+       if (code == QualityType.NULL)
+           return null;
        if (code == QualityType.INDEL)
         return "indel";
       if (code == QualityType.SNP)
@@ -479,6 +483,8 @@ public class MolecularSequence extends DomainResource {
     }
 
     public String toCode(RepositoryType code) {
+       if (code == RepositoryType.NULL)
+           return null;
        if (code == RepositoryType.DIRECTLINK)
         return "directlink";
       if (code == RepositoryType.OPENAPI)
@@ -623,6 +629,8 @@ public class MolecularSequence extends DomainResource {
     }
 
     public String toCode(SequenceType code) {
+       if (code == SequenceType.NULL)
+           return null;
        if (code == SequenceType.AA)
         return "aa";
       if (code == SequenceType.DNA)
@@ -745,6 +753,8 @@ public class MolecularSequence extends DomainResource {
     }
 
     public String toCode(StrandType code) {
+       if (code == StrandType.NULL)
+           return null;
        if (code == StrandType.WATSON)
         return "watson";
       if (code == StrandType.CRICK)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/NamingSystem.java

@@ -201,6 +201,8 @@ public class NamingSystem extends CanonicalResource {
     }
 
     public String toCode(NamingSystemIdentifierType code) {
+       if (code == NamingSystemIdentifierType.NULL)
+           return null;
        if (code == NamingSystemIdentifierType.OID)
         return "oid";
       if (code == NamingSystemIdentifierType.UUID)
@@ -346,6 +348,8 @@ public class NamingSystem extends CanonicalResource {
     }
 
     public String toCode(NamingSystemType code) {
+       if (code == NamingSystemType.NULL)
+           return null;
        if (code == NamingSystemType.CODESYSTEM)
         return "codesystem";
       if (code == NamingSystemType.IDENTIFIER)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Narrative.java

@@ -206,6 +206,8 @@ public class Narrative extends BaseNarrative implements INarrative {
     }
 
     public String toCode(NarrativeStatus code) {
+       if (code == NarrativeStatus.NULL)
+           return null;
        if (code == NarrativeStatus.GENERATED)
         return "generated";
       if (code == NarrativeStatus.EXTENSIONS)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/NutritionProduct.java

@@ -180,6 +180,8 @@ public class NutritionProduct extends DomainResource {
     }
 
     public String toCode(NutritionProductStatus code) {
+       if (code == NutritionProductStatus.NULL)
+           return null;
        if (code == NutritionProductStatus.ACTIVE)
         return "active";
       if (code == NutritionProductStatus.INACTIVE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ObservationDefinition.java

@@ -325,6 +325,8 @@ public class ObservationDefinition extends DomainResource {
     }
 
     public String toCode(ObservationDataType code) {
+       if (code == ObservationDataType.NULL)
+           return null;
        if (code == ObservationDataType.QUANTITY)
         return "Quantity";
       if (code == ObservationDataType.CODEABLECONCEPT)
@@ -482,6 +484,8 @@ public class ObservationDefinition extends DomainResource {
     }
 
     public String toCode(ObservationRangeCategory code) {
+       if (code == ObservationRangeCategory.NULL)
+           return null;
        if (code == ObservationRangeCategory.REFERENCE)
         return "reference";
       if (code == ObservationRangeCategory.CRITICAL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/OperationDefinition.java

@@ -161,6 +161,8 @@ public class OperationDefinition extends CanonicalResource {
     }
 
     public String toCode(OperationKind code) {
+       if (code == OperationKind.NULL)
+           return null;
        if (code == OperationKind.OPERATION)
         return "operation";
       if (code == OperationKind.QUERY)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/OperationOutcome.java

@@ -201,6 +201,8 @@ public class OperationOutcome extends DomainResource implements IBaseOperationOu
     }
 
     public String toCode(IssueSeverity code) {
+       if (code == IssueSeverity.NULL)
+           return null;
        if (code == IssueSeverity.FATAL)
         return "fatal";
       if (code == IssueSeverity.ERROR)
@@ -870,6 +872,8 @@ public class OperationOutcome extends DomainResource implements IBaseOperationOu
     }
 
     public String toCode(IssueType code) {
+       if (code == IssueType.NULL)
+           return null;
        if (code == IssueType.INVALID)
         return "invalid";
       if (code == IssueType.STRUCTURE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Patient.java

@@ -209,6 +209,8 @@ public class Patient extends DomainResource {
     }
 
     public String toCode(LinkType code) {
+       if (code == LinkType.NULL)
+           return null;
        if (code == LinkType.REPLACEDBY)
         return "replaced-by";
       if (code == LinkType.REPLACES)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Person.java

@@ -197,6 +197,8 @@ public class Person extends DomainResource {
     }
 
     public String toCode(IdentityAssuranceLevel code) {
+       if (code == IdentityAssuranceLevel.NULL)
+           return null;
        if (code == IdentityAssuranceLevel.LEVEL1)
         return "level1";
       if (code == IdentityAssuranceLevel.LEVEL2)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Provenance.java

@@ -230,6 +230,8 @@ public class Provenance extends DomainResource {
     }
 
     public String toCode(ProvenanceEntityRole code) {
+       if (code == ProvenanceEntityRole.NULL)
+           return null;
        if (code == ProvenanceEntityRole.DERIVATION)
         return "derivation";
       if (code == ProvenanceEntityRole.REVISION)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Questionnaire.java

@@ -163,6 +163,8 @@ public class Questionnaire extends CanonicalResource {
     }
 
     public String toCode(EnableWhenBehavior code) {
+       if (code == EnableWhenBehavior.NULL)
+           return null;
        if (code == EnableWhenBehavior.ALL)
         return "all";
       if (code == EnableWhenBehavior.ANY)
@@ -380,6 +382,8 @@ public class Questionnaire extends CanonicalResource {
     }
 
     public String toCode(QuestionnaireItemOperator code) {
+       if (code == QuestionnaireItemOperator.NULL)
+           return null;
        if (code == QuestionnaireItemOperator.EXISTS)
         return "exists";
       if (code == QuestionnaireItemOperator.EQUAL)
@@ -794,6 +798,8 @@ public class Questionnaire extends CanonicalResource {
     }
 
     public String toCode(QuestionnaireItemType code) {
+       if (code == QuestionnaireItemType.NULL)
+           return null;
        if (code == QuestionnaireItemType.GROUP)
         return "group";
       if (code == QuestionnaireItemType.DISPLAY)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/QuestionnaireResponse.java

@@ -221,6 +221,8 @@ public class QuestionnaireResponse extends DomainResource {
     }
 
     public String toCode(QuestionnaireResponseStatus code) {
+       if (code == QuestionnaireResponseStatus.NULL)
+           return null;
        if (code == QuestionnaireResponseStatus.INPROGRESS)
         return "in-progress";
       if (code == QuestionnaireResponseStatus.COMPLETED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/RelatedArtifact.java

@@ -280,6 +280,8 @@ public class RelatedArtifact extends DataType implements ICompositeType {
     }
 
     public String toCode(RelatedArtifactType code) {
+       if (code == RelatedArtifactType.NULL)
+           return null;
        if (code == RelatedArtifactType.DOCUMENTATION)
         return "documentation";
       if (code == RelatedArtifactType.JUSTIFICATION)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ResearchElementDefinition.java

@@ -181,6 +181,8 @@ public class ResearchElementDefinition extends CanonicalResource {
     }
 
     public String toCode(ResearchElementType code) {
+       if (code == ResearchElementType.NULL)
+           return null;
        if (code == ResearchElementType.POPULATION)
         return "population";
       if (code == ResearchElementType.EXPOSURE)
@@ -321,6 +323,8 @@ public class ResearchElementDefinition extends CanonicalResource {
     }
 
     public String toCode(VariableType code) {
+       if (code == VariableType.NULL)
+           return null;
        if (code == VariableType.DICHOTOMOUS)
         return "dichotomous";
       if (code == VariableType.CONTINUOUS)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ResearchStudy.java

@@ -335,6 +335,8 @@ public class ResearchStudy extends DomainResource {
     }
 
     public String toCode(ResearchStudyStatus code) {
+       if (code == ResearchStudyStatus.NULL)
+           return null;
        if (code == ResearchStudyStatus.ACTIVE)
         return "active";
       if (code == ResearchStudyStatus.ADMINISTRATIVELYCOMPLETED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/ResearchSubject.java

@@ -370,6 +370,8 @@ public class ResearchSubject extends DomainResource {
     }
 
     public String toCode(ResearchSubjectStatus code) {
+       if (code == ResearchSubjectStatus.NULL)
+           return null;
        if (code == ResearchSubjectStatus.CANDIDATE)
         return "candidate";
       if (code == ResearchSubjectStatus.ELIGIBLE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/SearchParameter.java

@@ -292,6 +292,8 @@ public class SearchParameter extends CanonicalResource {
     }
 
     public String toCode(SearchComparator code) {
+       if (code == SearchComparator.NULL)
+           return null;
        if (code == SearchComparator.EQ)
         return "eq";
       if (code == SearchComparator.NE)
@@ -620,6 +622,8 @@ public class SearchParameter extends CanonicalResource {
     }
 
     public String toCode(SearchModifierCode code) {
+       if (code == SearchModifierCode.NULL)
+           return null;
        if (code == SearchModifierCode.MISSING)
         return "missing";
       if (code == SearchModifierCode.EXACT)
@@ -818,6 +822,8 @@ public class SearchParameter extends CanonicalResource {
     }
 
     public String toCode(XPathUsageType code) {
+       if (code == XPathUsageType.NULL)
+           return null;
        if (code == XPathUsageType.NORMAL)
         return "normal";
       if (code == XPathUsageType.PHONETIC)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Slot.java

@@ -217,6 +217,8 @@ public class Slot extends DomainResource {
     }
 
     public String toCode(SlotStatus code) {
+       if (code == SlotStatus.NULL)
+           return null;
        if (code == SlotStatus.BUSY)
         return "busy";
       if (code == SlotStatus.FREE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Specimen.java

@@ -198,6 +198,8 @@ public class Specimen extends DomainResource {
     }
 
     public String toCode(SpecimenStatus code) {
+       if (code == SpecimenStatus.NULL)
+           return null;
        if (code == SpecimenStatus.AVAILABLE)
         return "available";
       if (code == SpecimenStatus.UNAVAILABLE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/SpecimenDefinition.java

@@ -161,6 +161,8 @@ public class SpecimenDefinition extends DomainResource {
     }
 
     public String toCode(SpecimenContainedPreference code) {
+       if (code == SpecimenContainedPreference.NULL)
+           return null;
        if (code == SpecimenContainedPreference.PREFERRED)
         return "preferred";
       if (code == SpecimenContainedPreference.ALTERNATE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/StructureDefinition.java

@@ -185,6 +185,8 @@ public class StructureDefinition extends CanonicalResource {
     }
 
     public String toCode(ExtensionContextType code) {
+       if (code == ExtensionContextType.NULL)
+           return null;
        if (code == ExtensionContextType.FHIRPATH)
         return "fhirpath";
       if (code == ExtensionContextType.ELEMENT)
@@ -355,6 +357,8 @@ public class StructureDefinition extends CanonicalResource {
     }
 
     public String toCode(StructureDefinitionKind code) {
+       if (code == StructureDefinitionKind.NULL)
+           return null;
        if (code == StructureDefinitionKind.PRIMITIVETYPE)
         return "primitive-type";
       if (code == StructureDefinitionKind.COMPLEXTYPE)
@@ -480,6 +484,8 @@ public class StructureDefinition extends CanonicalResource {
     }
 
     public String toCode(TypeDerivationRule code) {
+       if (code == TypeDerivationRule.NULL)
+           return null;
        if (code == TypeDerivationRule.SPECIALIZATION)
         return "specialization";
       if (code == TypeDerivationRule.CONSTRAINT)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/StructureMap.java

@@ -163,6 +163,8 @@ public class StructureMap extends CanonicalResource {
     }
 
     public String toCode(StructureMapContextType code) {
+       if (code == StructureMapContextType.NULL)
+           return null;
        if (code == StructureMapContextType.TYPE)
         return "type";
       if (code == StructureMapContextType.VARIABLE)
@@ -302,6 +304,8 @@ public class StructureMap extends CanonicalResource {
     }
 
     public String toCode(StructureMapGroupTypeMode code) {
+       if (code == StructureMapGroupTypeMode.NULL)
+           return null;
        if (code == StructureMapGroupTypeMode.NONE)
         return "none";
       if (code == StructureMapGroupTypeMode.TYPES)
@@ -424,6 +428,8 @@ public class StructureMap extends CanonicalResource {
     }
 
     public String toCode(StructureMapInputMode code) {
+       if (code == StructureMapInputMode.NULL)
+           return null;
        if (code == StructureMapInputMode.SOURCE)
         return "source";
       if (code == StructureMapInputMode.TARGET)
@@ -584,6 +590,8 @@ public class StructureMap extends CanonicalResource {
     }
 
     public String toCode(StructureMapModelMode code) {
+       if (code == StructureMapModelMode.NULL)
+           return null;
        if (code == StructureMapModelMode.SOURCE)
         return "source";
       if (code == StructureMapModelMode.QUERIED)
@@ -762,6 +770,8 @@ public class StructureMap extends CanonicalResource {
     }
 
     public String toCode(StructureMapSourceListMode code) {
+       if (code == StructureMapSourceListMode.NULL)
+           return null;
        if (code == StructureMapSourceListMode.FIRST)
         return "first";
       if (code == StructureMapSourceListMode.NOTFIRST)
@@ -929,6 +939,8 @@ public class StructureMap extends CanonicalResource {
     }
 
     public String toCode(StructureMapTargetListMode code) {
+       if (code == StructureMapTargetListMode.NULL)
+           return null;
        if (code == StructureMapTargetListMode.FIRST)
         return "first";
       if (code == StructureMapTargetListMode.SHARE)
@@ -1333,6 +1345,8 @@ public class StructureMap extends CanonicalResource {
     }
 
     public String toCode(StructureMapTransform code) {
+       if (code == StructureMapTransform.NULL)
+           return null;
        if (code == StructureMapTransform.CREATE)
         return "create";
       if (code == StructureMapTransform.COPY)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Subscription.java

@@ -225,6 +225,8 @@ public class Subscription extends DomainResource {
     }
 
     public String toCode(SubscriptionChannelType code) {
+       if (code == SubscriptionChannelType.NULL)
+           return null;
        if (code == SubscriptionChannelType.RESTHOOK)
         return "rest-hook";
       if (code == SubscriptionChannelType.WEBSOCKET)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/SubscriptionStatus.java

@@ -218,6 +218,8 @@ public class SubscriptionStatus extends DomainResource {
     }
 
     public String toCode(SubscriptionNotificationType code) {
+       if (code == SubscriptionNotificationType.NULL)
+           return null;
        if (code == SubscriptionNotificationType.HANDSHAKE)
         return "handshake";
       if (code == SubscriptionNotificationType.HEARTBEAT)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/SubscriptionTopic.java

@@ -163,6 +163,8 @@ public class SubscriptionTopic extends DomainResource {
     }
 
     public String toCode(CriteriaNotExistsBehavior code) {
+       if (code == CriteriaNotExistsBehavior.NULL)
+           return null;
        if (code == CriteriaNotExistsBehavior.TESTPASSES)
         return "test-passes";
       if (code == CriteriaNotExistsBehavior.TESTFAILS)
@@ -301,6 +303,8 @@ public class SubscriptionTopic extends DomainResource {
     }
 
     public String toCode(InteractionTrigger code) {
+       if (code == InteractionTrigger.NULL)
+           return null;
        if (code == InteractionTrigger.CREATE)
         return "create";
       if (code == InteractionTrigger.UPDATE)
@@ -677,6 +681,8 @@ public class SubscriptionTopic extends DomainResource {
     }
 
     public String toCode(SubscriptionSearchModifier code) {
+       if (code == SubscriptionSearchModifier.NULL)
+           return null;
        if (code == SubscriptionSearchModifier.EQUAL)
         return "=";
       if (code == SubscriptionSearchModifier.EQ)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Substance.java

@@ -178,6 +178,8 @@ public class Substance extends DomainResource {
     }
 
     public String toCode(FHIRSubstanceStatus code) {
+       if (code == FHIRSubstanceStatus.NULL)
+           return null;
        if (code == FHIRSubstanceStatus.ACTIVE)
         return "active";
       if (code == FHIRSubstanceStatus.INACTIVE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/SupplyDelivery.java

@@ -198,6 +198,8 @@ public class SupplyDelivery extends DomainResource {
     }
 
     public String toCode(SupplyDeliveryStatus code) {
+       if (code == SupplyDeliveryStatus.NULL)
+           return null;
        if (code == SupplyDeliveryStatus.INPROGRESS)
         return "in-progress";
       if (code == SupplyDeliveryStatus.COMPLETED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/SupplyRequest.java

@@ -259,6 +259,8 @@ public class SupplyRequest extends DomainResource {
     }
 
     public String toCode(SupplyRequestStatus code) {
+       if (code == SupplyRequestStatus.NULL)
+           return null;
        if (code == SupplyRequestStatus.DRAFT)
         return "draft";
       if (code == SupplyRequestStatus.ACTIVE)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Task.java

@@ -300,6 +300,8 @@ public class Task extends DomainResource {
     }
 
     public String toCode(TaskIntent code) {
+       if (code == TaskIntent.NULL)
+           return null;
        if (code == TaskIntent.UNKNOWN)
         return "unknown";
       if (code == TaskIntent.PROPOSAL)
@@ -620,6 +622,8 @@ public class Task extends DomainResource {
     }
 
     public String toCode(TaskStatus code) {
+       if (code == TaskStatus.NULL)
+           return null;
        if (code == TaskStatus.DRAFT)
         return "draft";
       if (code == TaskStatus.REQUESTED)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/TerminologyCapabilities.java

@@ -165,6 +165,8 @@ public class TerminologyCapabilities extends CanonicalResource {
     }
 
     public String toCode(CodeSearchSupport code) {
+       if (code == CodeSearchSupport.NULL)
+           return null;
        if (code == CodeSearchSupport.EXPLICIT)
         return "explicit";
       if (code == CodeSearchSupport.ALL)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/TestReport.java

@@ -215,6 +215,8 @@ public class TestReport extends DomainResource {
     }
 
     public String toCode(TestReportActionResult code) {
+       if (code == TestReportActionResult.NULL)
+           return null;
        if (code == TestReportActionResult.PASS)
         return "pass";
       if (code == TestReportActionResult.SKIP)
@@ -359,6 +361,8 @@ public class TestReport extends DomainResource {
     }
 
     public String toCode(TestReportParticipantType code) {
+       if (code == TestReportParticipantType.NULL)
+           return null;
        if (code == TestReportParticipantType.TESTENGINE)
         return "test-engine";
       if (code == TestReportParticipantType.CLIENT)
@@ -499,6 +503,8 @@ public class TestReport extends DomainResource {
     }
 
     public String toCode(TestReportResult code) {
+       if (code == TestReportResult.NULL)
+           return null;
        if (code == TestReportResult.PASS)
         return "pass";
       if (code == TestReportResult.FAIL)
@@ -675,6 +681,8 @@ public class TestReport extends DomainResource {
     }
 
     public String toCode(TestReportStatus code) {
+       if (code == TestReportStatus.NULL)
+           return null;
        if (code == TestReportStatus.COMPLETED)
         return "completed";
       if (code == TestReportStatus.INPROGRESS)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/TestScript.java

@@ -161,6 +161,8 @@ public class TestScript extends CanonicalResource {
     }
 
     public String toCode(AssertionDirectionType code) {
+       if (code == AssertionDirectionType.NULL)
+           return null;
        if (code == AssertionDirectionType.RESPONSE)
         return "response";
       if (code == AssertionDirectionType.REQUEST)
@@ -443,6 +445,8 @@ public class TestScript extends CanonicalResource {
     }
 
     public String toCode(AssertionOperatorType code) {
+       if (code == AssertionOperatorType.NULL)
+           return null;
        if (code == AssertionOperatorType.EQUALS)
         return "equals";
       if (code == AssertionOperatorType.NOTEQUALS)
@@ -761,6 +765,8 @@ public class TestScript extends CanonicalResource {
     }
 
     public String toCode(AssertionResponseTypes code) {
+       if (code == AssertionResponseTypes.NULL)
+           return null;
        if (code == AssertionResponseTypes.OKAY)
         return "okay";
       if (code == AssertionResponseTypes.CREATED)
@@ -4928,6 +4934,8 @@ public class TestScript extends CanonicalResource {
     }
 
     public String toCode(FHIRDefinedType code) {
+       if (code == FHIRDefinedType.NULL)
+           return null;
        if (code == FHIRDefinedType.ADDRESS)
         return "Address";
       if (code == FHIRDefinedType.AGE)
@@ -5550,6 +5558,8 @@ public class TestScript extends CanonicalResource {
     }
 
     public String toCode(TestScriptRequestMethodCode code) {
+       if (code == TestScriptRequestMethodCode.NULL)
+           return null;
        if (code == TestScriptRequestMethodCode.DELETE)
         return "delete";
       if (code == TestScriptRequestMethodCode.GET)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/Timing.java

@@ -609,6 +609,8 @@ public class Timing extends BackboneType implements ICompositeType {
     }
 
     public String toCode(EventTiming code) {
+       if (code == EventTiming.NULL)
+           return null;
        if (code == EventTiming.MORN)
         return "MORN";
       if (code == EventTiming.MORN_EARLY)
@@ -867,6 +869,8 @@ public class Timing extends BackboneType implements ICompositeType {
     }
 
     public String toCode(UnitsOfTime code) {
+       if (code == UnitsOfTime.NULL)
+           return null;
        if (code == UnitsOfTime.S)
         return "s";
       if (code == UnitsOfTime.MIN)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/TriggerDefinition.java

@@ -273,6 +273,8 @@ public class TriggerDefinition extends DataType implements ICompositeType {
     }
 
     public String toCode(TriggerType code) {
+       if (code == TriggerType.NULL)
+           return null;
        if (code == TriggerType.NAMEDEVENT)
         return "named-event";
       if (code == TriggerType.PERIODIC)

org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/model/VerificationResult.java

@@ -233,6 +233,8 @@ public class VerificationResult extends DomainResource {
     }
 
     public String toCode(Status code) {
+       if (code == Status.NULL)
+           return null;
        if (code == Status.ATTESTED)
         return "attested";
       if (code == Status.VALIDATED)