diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor30.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor30.java
index d43a785f1..cc7eb0da6 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor30.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor30.java
@@ -33,14 +33,54 @@ package org.hl7.fhir.convertors;
 
 import org.hl7.fhir.exceptions.FHIRException;
 
+/**
+ * This interface is passed into the version conversion routines when on of the
+ * converters is producing or converting R3 resources. 
+ * 
+ * The interface allows users of the code to 
+ *   1. manage the life cycle of new resources created (or needed) during the conversion process
+ *   2. manage how unknown content etc is handled
+ *    
+ * @author grahame
+ *
+ */
 public interface VersionConvertorAdvisor30 {
+  
+  /**
+   * when processing a bundle, and converting from R3 to R2 whether to ignore an entry in the bundle. 
+   * typically, return true when it's a resource that isn't handled, and you don't care. 
+   * 
+   * by default, always return false unless you know why not do this
+   * 
+   * todo: why only R2? generalise this to all targets
+   * 
+   * @param src
+   * @return
+   */
   boolean ignoreEntry(org.hl7.fhir.dstu3.model.Bundle.BundleEntryComponent src);
 
-  // called ?
-  org.hl7.fhir.dstu2.model.Resource convert(org.hl7.fhir.dstu3.model.Resource resource) throws FHIRException;
-
-  // called when an r2 value set has a codeSystem in it
+  /**
+   * In R2, code systems are internal to value sets, but in subsequent versions, they
+   * exist as separate resources. The convertor will create the code system, and then
+   * call this routine for the host to decide what to do with it
+   * 
+   * It can make it a contained resource, or it can put it somewhere else
+   * 
+   * @param tgtcs
+   * @param source
+   * @throws FHIRException
+   */
   void handleCodeSystem(org.hl7.fhir.dstu3.model.CodeSystem tgtcs, org.hl7.fhir.dstu3.model.ValueSet source) throws FHIRException;
 
+  /** 
+   * when converting from R3 to R2, and converting a value set, the convertor will need 
+   * to find the code system a value set is referring to, so it can include it inline. 
+   * 
+   * This routine should find the actual resource
+   *  
+   * @param src
+   * @return
+   * @throws FHIRException
+   */
   org.hl7.fhir.dstu3.model.CodeSystem getCodeSystem(org.hl7.fhir.dstu3.model.ValueSet src) throws FHIRException;
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor40.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor40.java
index 0f6e2cae4..7a5774be8 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor40.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor40.java
@@ -33,16 +33,55 @@ package org.hl7.fhir.convertors;
 
 import org.hl7.fhir.exceptions.FHIRException;
 
+
+/**
+ * This interface is passed into the version conversion routines when on of the
+ * converters is producing or converting R4 resources. 
+ * 
+ * The interface allows users of the code to 
+ *   1. manage the life cycle of new resources created (or needed) during the conversion process
+ *   2. manage how unknown content etc is handled
+ *    
+ * @author grahame
+ *
+ */
 public interface VersionConvertorAdvisor40 {
+  
+  /**
+   * when processing a bundle, and converting from R4 to R2 whether to ignore an entry in the bundle. 
+   * typically, return true when it's a resource that isn't handled, and you don't care. 
+   * 
+   * by default, always return false unless you know why not do this
+   * 
+   * todo: why only R2? generalise this to all targets
+   * 
+   * @param src
+   * @return
+   */
   boolean ignoreEntry(org.hl7.fhir.r4.model.Bundle.BundleEntryComponent src);
 
-  // called ?
-  org.hl7.fhir.dstu2.model.Resource convertR2(org.hl7.fhir.r4.model.Resource resource) throws FHIRException;
-  org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r4.model.Resource resource) throws FHIRException;
-  org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r4.model.Resource resource) throws FHIRException;
-
-  // called when an r2 value set has a codeSystem in it
+  /**
+   * In R2, code systems are internal to value sets, but in subsequent versions, they
+   * exist as separate resources. The convertor will create the code system, and then
+   * call this routine for the host to decide what to do with it
+   * 
+   * It can make it a contained resource, or it can put it somewhere else
+   * 
+   * @param tgtcs
+   * @param source
+   * @throws FHIRException
+   */
   void handleCodeSystem(org.hl7.fhir.r4.model.CodeSystem tgtcs, org.hl7.fhir.r4.model.ValueSet source) throws FHIRException;
 
+  /** 
+   * when converting from R4 to R2, and converting a value set, the convertor will need 
+   * to find the code system a value set is referring to, so it can include it inline. 
+   * 
+   * This routine should find the actual resource
+   *  
+   * @param src
+   * @return
+   * @throws FHIRException
+   */
   org.hl7.fhir.r4.model.CodeSystem getCodeSystem(org.hl7.fhir.r4.model.ValueSet src) throws FHIRException;
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor50.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor50.java
index 0c697173a..25072549d 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor50.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/VersionConvertorAdvisor50.java
@@ -34,16 +34,41 @@ package org.hl7.fhir.convertors;
 import org.hl7.fhir.exceptions.FHIRException;
 
 public interface VersionConvertorAdvisor50 {
+  /**
+   * when processing a bundle, and converting from R5 to R2 whether to ignore an entry in the bundle. 
+   * typically, return true when it's a resource that isn't handled, and you don't care. 
+   * 
+   * by default, always return false unless you know why not do this
+   * 
+   * todo: why only R2? generalise this to all targets
+   * 
+   * @param src
+   * @return
+   */
   boolean ignoreEntry(org.hl7.fhir.r5.model.Bundle.BundleEntryComponent src);
 
-  // called ?
-  org.hl7.fhir.dstu2.model.Resource convertR2(org.hl7.fhir.r5.model.Resource resource) throws FHIRException;
-  org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r5.model.Resource resource) throws FHIRException;
-  org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r5.model.Resource resource) throws FHIRException;
-  org.hl7.fhir.r4.model.Resource convertR4(org.hl7.fhir.r5.model.Resource resource) throws FHIRException;
-
-  // called when an r2 value set has a codeSystem in it
+  /**
+   * In R2, code systems are internal to value sets, but in subsequent versions, they
+   * exist as separate resources. The convertor will create the code system, and then
+   * call this routine for the host to decide what to do with it
+   * 
+   * It can make it a contained resource, or it can put it somewhere else
+   * 
+   * @param tgtcs
+   * @param source
+   * @throws FHIRException
+   */
   void handleCodeSystem(org.hl7.fhir.r5.model.CodeSystem tgtcs, org.hl7.fhir.r5.model.ValueSet source) throws FHIRException;
 
+  /** 
+   * when converting from R5 to R2, and converting a value set, the convertor will need 
+   * to find the code system a value set is referring to, so it can include it inline. 
+   * 
+   * This routine should find the actual resource
+   *  
+   * @param src
+   * @return
+   * @throws FHIRException
+   */
   org.hl7.fhir.r5.model.CodeSystem getCodeSystem(org.hl7.fhir.r5.model.ValueSet src) throws FHIRException;
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_30/Bundle10_30.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_30/Bundle10_30.java
index 6ad1c12a9..23fb51626 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_30/Bundle10_30.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_30/Bundle10_30.java
@@ -52,9 +52,7 @@ public class Bundle10_30 {
         for (org.hl7.fhir.dstu3.model.Bundle.BundleLinkComponent t : src.getLink()) tgt.addLink(convertBundleLinkComponent(t));
         if (src.hasFullUrlElement())
             tgt.setFullUrlElement(VersionConvertor_10_30.convertUri(src.getFullUrlElement()));
-        org.hl7.fhir.dstu2.model.Resource res = advisor.convert(src.getResource());
-        if (res == null)
-            res = VersionConvertor_10_30.convertResource(src.getResource());
+        org.hl7.fhir.dstu2.model.Resource res = VersionConvertor_10_30.convertResource(src.getResource());
         tgt.setResource(res);
         if (src.hasSearch())
             tgt.setSearch(convertBundleEntrySearchComponent(src.getSearch()));
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_40/Bundle10_40.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_40/Bundle10_40.java
index 35b7a9d56..4e413e43d 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_40/Bundle10_40.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_40/Bundle10_40.java
@@ -71,9 +71,7 @@ public class Bundle10_40 {
         for (org.hl7.fhir.r4.model.Bundle.BundleLinkComponent t : src.getLink()) tgt.addLink(convertBundleLinkComponent(t));
         if (src.hasFullUrlElement())
             tgt.setFullUrlElement(VersionConvertor_10_40.convertUri(src.getFullUrlElement()));
-        org.hl7.fhir.dstu2.model.Resource res = advisor.convertR2(src.getResource());
-        if (res == null)
-            res = VersionConvertor_10_40.convertResource(src.getResource());
+        org.hl7.fhir.dstu2.model.Resource res = VersionConvertor_10_40.convertResource(src.getResource());
         tgt.setResource(res);
         if (src.hasSearch())
             tgt.setSearch(convertBundleEntrySearchComponent(src.getSearch()));
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_50/Bundle10_50.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_50/Bundle10_50.java
index 13a80b9d2..df8de9f2c 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_50/Bundle10_50.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_50/Bundle10_50.java
@@ -71,9 +71,7 @@ public class Bundle10_50 {
         for (org.hl7.fhir.r5.model.Bundle.BundleLinkComponent t : src.getLink()) tgt.addLink(convertBundleLinkComponent(t));
         if (src.hasFullUrlElement())
             tgt.setFullUrlElement(VersionConvertor_10_50.convertUri(src.getFullUrlElement()));
-        org.hl7.fhir.dstu2.model.Resource res = advisor.convertR2(src.getResource());
-        if (res == null)
-            res = VersionConvertor_10_50.convertResource(src.getResource());
+        org.hl7.fhir.dstu2.model.Resource res = VersionConvertor_10_50.convertResource(src.getResource());
         tgt.setResource(res);
         if (src.hasSearch())
             tgt.setSearch(convertBundleEntrySearchComponent(src.getSearch()));
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2016MayToR4Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2016MayToR4Loader.java
index 94249ead4..0e8eac879 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2016MayToR4Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2016MayToR4Loader.java
@@ -116,21 +116,6 @@ public class R2016MayToR4Loader extends BaseLoaderR4 implements IContextResource
     return false;
   }
 
-  @Override
-  public org.hl7.fhir.dstu2.model.Resource convertR2(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public Resource convertR2016May(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
     cs.setId(vs.getId());
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2016MayToR5Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2016MayToR5Loader.java
index 4aa7b132a..90ef54953 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2016MayToR5Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2016MayToR5Loader.java
@@ -163,21 +163,6 @@ public class R2016MayToR5Loader extends BaseLoaderR5 implements VersionConvertor
     return false;
   }
 
-  @Override
-  public org.hl7.fhir.dstu2.model.Resource convertR2(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public Resource convertR2016May(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
     cs.setId(vs.getId());
@@ -191,11 +176,5 @@ public class R2016MayToR5Loader extends BaseLoaderR5 implements VersionConvertor
     return null;
   }
 
-  @Override
-  public org.hl7.fhir.r4.model.Resource convertR4(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
- 
 
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR3Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR3Loader.java
index 1bed6644a..33ef1d454 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR3Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR3Loader.java
@@ -113,10 +113,6 @@ public class R2ToR3Loader extends BaseLoaderR3 implements VersionConvertorAdviso
     return false;
   }
 
-  @Override
-  public Resource convert(org.hl7.fhir.dstu3.model.Resource resource) throws FHIRException {
-    return null;
-  }
 
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR4Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR4Loader.java
index 941acbd4b..40ec42877 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR4Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR4Loader.java
@@ -115,20 +115,6 @@ public class R2ToR4Loader extends BaseLoaderR4 implements VersionConvertorAdviso
     return false;
   }
 
-  @Override
-  public Resource convertR2(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
     cs.setId(vs.getId());
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR5Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR5Loader.java
index 07f64c869..91f69b4e2 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR5Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R2ToR5Loader.java
@@ -163,20 +163,6 @@ public class R2ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
     return false;
   }
 
-  @Override
-  public Resource convertR2(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
     cs.setId(vs.getId());
@@ -190,10 +176,5 @@ public class R2ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
     return null;
   }
 
-  @Override
-  public org.hl7.fhir.r4.model.Resource convertR4(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
 
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R3ToR4Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R3ToR4Loader.java
index 0691b1fe6..46ae2d6da 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R3ToR4Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R3ToR4Loader.java
@@ -125,20 +125,6 @@ public class R3ToR4Loader extends BaseLoaderR4 implements IContextResourceLoader
     return false;
   }
 
-  @Override
-  public org.hl7.fhir.dstu2.model.Resource convertR2(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public Resource convertR3(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
 
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R3ToR5Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R3ToR5Loader.java
index 07feac9ab..e08f45a33 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R3ToR5Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R3ToR5Loader.java
@@ -166,21 +166,6 @@ public class R3ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
     return false;
   }
 
-  @Override
-  public org.hl7.fhir.dstu2.model.Resource convertR2(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public Resource convertR3(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
     cs.setId(vs.getId());
@@ -194,9 +179,4 @@ public class R3ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
     return null;
   }
 
-  @Override
-  public org.hl7.fhir.r4.model.Resource convertR4(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R4ToR5Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R4ToR5Loader.java
index fa8af1b5f..3f9001daf 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R4ToR5Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R4ToR5Loader.java
@@ -166,21 +166,6 @@ public class R4ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
     return false;
   }
 
-  @Override
-  public org.hl7.fhir.dstu2.model.Resource convertR2(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public Resource convertR4(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
     cs.setId(vs.getId());
@@ -194,9 +179,4 @@ public class R4ToR5Loader extends BaseLoaderR5 implements IContextResourceLoader
     return null;
   }
 
-  @Override
-  public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R5ToR5Loader.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R5ToR5Loader.java
index a71cb3705..1046b11e4 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R5ToR5Loader.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/loaders/R5ToR5Loader.java
@@ -163,21 +163,6 @@ public class R5ToR5Loader extends BaseLoaderR5 implements VersionConvertorAdviso
     return false;
   }
 
-  @Override
-  public org.hl7.fhir.dstu2.model.Resource convertR2(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.r4.model.Resource convertR4(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
     cs.setId(vs.getId());
@@ -191,9 +176,4 @@ public class R5ToR5Loader extends BaseLoaderR5 implements VersionConvertorAdviso
     return null;
   }
 
-  @Override
-  public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGPackConverter102.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGPackConverter102.java
index 32cedac2d..385545f4b 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGPackConverter102.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGPackConverter102.java
@@ -89,10 +89,6 @@ public class IGPackConverter102 implements VersionConvertorAdvisor30 {
     return false;
   }
 
-  @Override
-  public Resource convert(org.hl7.fhir.dstu3.model.Resource resource) throws FHIRException {
-    return null;
-  }
 
   @Override
   public void handleCodeSystem(CodeSystem tgtcs, ValueSet vs) {
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGR2ConvertorAdvisor.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGR2ConvertorAdvisor.java
index ceac2feae..b2fe5bfa9 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGR2ConvertorAdvisor.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGR2ConvertorAdvisor.java
@@ -46,20 +46,7 @@ public class IGR2ConvertorAdvisor implements VersionConvertorAdvisor40 {
     return false;
   }
 
-  @Override
-  public Resource convertR2(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
 
-  @Override
-  public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-    return null;
-  }
 
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGR2ConvertorAdvisor5.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGR2ConvertorAdvisor5.java
index 132c2bcbe..20ae18af3 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGR2ConvertorAdvisor5.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/IGR2ConvertorAdvisor5.java
@@ -46,21 +46,6 @@ public class IGR2ConvertorAdvisor5 implements VersionConvertorAdvisor50 {
     return false;
   }
 
-  @Override
-  public Resource convertR2(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
-  @Override
-  public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
   @Override
   public void handleCodeSystem(CodeSystem cs, ValueSet vs) {
     cs.setId(vs.getId());
@@ -71,9 +56,4 @@ public class IGR2ConvertorAdvisor5 implements VersionConvertorAdvisor50 {
     return null;
   }
 
-  @Override
-  public org.hl7.fhir.r4.model.Resource convertR4(org.hl7.fhir.r5.model.Resource resource) throws FHIRException {
-    return null;
-  }
-
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/NpmPackageVersionConverter.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/NpmPackageVersionConverter.java
index 4f63e27fa..72282bd65 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/NpmPackageVersionConverter.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/misc/NpmPackageVersionConverter.java
@@ -50,20 +50,6 @@ public class NpmPackageVersionConverter {
       return false;
     }
 
-    @Override
-    public Resource convertR2(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-      throw new Error("Not done yet");
-    }
-
-    @Override
-    public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-      throw new Error("Not done yet");
-    }
-
-    @Override
-    public org.hl7.fhir.dstu3.model.Resource convertR3(org.hl7.fhir.r4.model.Resource resource) throws FHIRException {
-      throw new Error("Not done yet");
-    }
 
     @Override
     public void handleCodeSystem(CodeSystem tgtcs, ValueSet source) throws FHIRException {
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/NativeHostServices.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/NativeHostServices.java
index 00b5cb9db..f54d8d2a7 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/NativeHostServices.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/NativeHostServices.java
@@ -108,21 +108,6 @@ public class NativeHostServices {
       return false;
     }
 
-    @Override
-    public org.hl7.fhir.dstu2016may.model.Resource convertR2016May(Resource resource) throws FHIRException {
-      return null;
-    }
-
-    @Override
-    public org.hl7.fhir.dstu2.model.Resource convertR2(Resource resource) throws FHIRException {
-      return null;
-    }
-
-    @Override
-    public org.hl7.fhir.dstu3.model.Resource convertR3(Resource resource) throws FHIRException {
-      return null;
-    }
-
     @Override
     public void handleCodeSystem(CodeSystem tgtcs, ValueSet source) throws FHIRException {
     }
@@ -132,12 +117,6 @@ public class NativeHostServices {
       throw new FHIRException("Code systems cannot be handled at this time"); // what to do? need thread local storage? 
     }
 
-    @Override
-    public org.hl7.fhir.r4.model.Resource convertR4(Resource resource) throws FHIRException {
-      // still to do
-      return null;
-    }
-
   }
 
   private ValidationEngine validator;