Allow Subscription to be configured to send delete messages (#3245)

* Allow Subscription to be configured to send delete messages

* Add tests and implement MR suggestions

Co-authored-by: juan.marchionatto <juan.marchionatto@smilecdr.com>

hapi-fhir-base/src/main/java/ca/uhn/fhir/util/HapiExtensions.java

@@ -130,6 +130,11 @@ public class HapiExtensions {
 	 */
 	public static final String EX_RETRY_COUNT = "http://hapifhir.io/fhir/StructureDefinition/subscription-delivery-retry-count";
 
+	/**
+	 * This extension provides a way for subscribers to indicate if DELETE messages must be sent (default is ignoring them)
+	 */
+	public static final String EX_SEND_DELETE_MESSAGES = "http://hapifhir.io/fhir/StructureDefinition/subscription-send-delete-messages";
+
 	/**
 	 * Non instantiable
 	 */

hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/5_7_0/3243-allow-rest-hook-subscription-to-send-delete-requests.yaml

@@ -0,0 +1,4 @@
+---
+type: add
+issue: 3243
+title: "Allow Rest Hook subscriptions to be configured to send delete requests."

hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/subscription/BaseSubscriptionsR4Test.java

@@ -17,6 +17,7 @@ import org.hl7.fhir.instance.model.api.IIdType;
 import org.hl7.fhir.r4.model.Bundle;
 import org.hl7.fhir.r4.model.CodeableConcept;
 import org.hl7.fhir.r4.model.Coding;
+import org.hl7.fhir.r4.model.Extension;
 import org.hl7.fhir.r4.model.Observation;
 import org.hl7.fhir.r4.model.Organization;
 import org.hl7.fhir.r4.model.Patient;
@@ -109,7 +110,14 @@ public abstract class BaseSubscriptionsR4Test extends BaseResourceProviderR4Test
 
 
 	protected Subscription createSubscription(String theCriteria, String thePayload) {
+		return createSubscription(theCriteria, thePayload, null);
+	}
+
+	protected Subscription createSubscription(String theCriteria, String thePayload, Extension theExtension) {
 		Subscription subscription = newSubscription(theCriteria, thePayload);
+		if (theExtension != null) {
+			subscription.getExtension().add(theExtension);
+		}
 
 		MethodOutcome methodOutcome = myClient.create().resource(subscription).execute();
 		subscription.setId(methodOutcome.getId().getIdPart());

hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/subscription/resthook/RestHookTestR4Test.java

@@ -3,6 +3,7 @@ package ca.uhn.fhir.jpa.subscription.resthook;
 import ca.uhn.fhir.jpa.api.config.DaoConfig;
 import ca.uhn.fhir.jpa.config.StoppableSubscriptionDeliveringRestHookSubscriber;
 import ca.uhn.fhir.jpa.subscription.BaseSubscriptionsR4Test;
+import ca.uhn.fhir.model.primitive.IdDt;
 import ca.uhn.fhir.rest.api.CacheControlDirective;
 import ca.uhn.fhir.rest.api.Constants;
 import ca.uhn.fhir.rest.api.MethodOutcome;
@@ -15,6 +16,7 @@ import org.hl7.fhir.r4.model.Bundle;
 import org.hl7.fhir.r4.model.CodeableConcept;
 import org.hl7.fhir.r4.model.Coding;
 import org.hl7.fhir.r4.model.Enumerations;
+import org.hl7.fhir.r4.model.Extension;
 import org.hl7.fhir.r4.model.IdType;
 import org.hl7.fhir.r4.model.Meta;
 import org.hl7.fhir.r4.model.Observation;
@@ -32,6 +34,7 @@ import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
+import static ca.uhn.fhir.util.HapiExtensions.EX_SEND_DELETE_MESSAGES;
 import static org.awaitility.Awaitility.await;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
@@ -514,6 +517,39 @@ public class RestHookTestR4Test extends BaseSubscriptionsR4Test {
 		assertEquals("changed", observation2.getNoteFirstRep().getText());
 	}
 
+
+	@Test
+	public void RestHookSubscriptionWithPayloadSendsDeleteRequest() throws Exception {
+		String payload = "application/json";
+		String criteria1 = "[*]";
+
+		Extension sendDeleteMessagesExtension = new Extension()
+			.setUrl(EX_SEND_DELETE_MESSAGES)
+			.setValue(new BooleanType(true));
+
+		waitForActivatedSubscriptionCount(0);
+		createSubscription(criteria1, payload, sendDeleteMessagesExtension);
+		waitForActivatedSubscriptionCount(1);
+
+		myStoppableSubscriptionDeliveringRestHookSubscriber.pause();
+		final CountDownLatch countDownLatch = new CountDownLatch(1);
+		myStoppableSubscriptionDeliveringRestHookSubscriber.setCountDownLatch(countDownLatch);
+
+		ourLog.info("** About to send observation");
+		Observation observation = sendObservation("OB-01", "SNOMED-CT");
+		assertEquals("1", observation.getIdElement().getVersionIdPart());
+
+		// Wait for our delivery channel thread to be paused
+		assertTrue(countDownLatch.await(5L, TimeUnit.SECONDS));
+		// Open the floodgates!
+		myStoppableSubscriptionDeliveringRestHookSubscriber.unPause();
+
+		ourLog.info("** About to delete observation");
+		myObservationDao.delete(IdDt.of(observation).toUnqualifiedVersionless());
+		ourObservationProvider.waitForDeleteCount(1);
+	}
+
+
 	@Test
 	public void testRestHookSubscriptionGetsLatestVersionWithFlag() throws Exception {
 		String payload = "application/json";

hapi-fhir-jpaserver-subscription/src/main/java/ca/uhn/fhir/jpa/subscription/match/deliver/resthook/SubscriptionDeliveringRestHookSubscriber.java

@@ -45,6 +45,7 @@ import ca.uhn.fhir.rest.client.interceptor.SimpleRequestHeaderInterceptor;
 import ca.uhn.fhir.rest.gclient.IClientExecutable;
 import ca.uhn.fhir.rest.server.exceptions.ResourceGoneException;
 import ca.uhn.fhir.rest.server.exceptions.ResourceNotFoundException;
+import ca.uhn.fhir.rest.server.messaging.BaseResourceModifiedMessage;
 import ca.uhn.fhir.util.BundleBuilder;
 import org.apache.commons.text.StringSubstitutor;
 import org.hl7.fhir.instance.model.api.IBaseResource;
@@ -164,11 +165,11 @@ public class SubscriptionDeliveringRestHookSubscriber extends BaseSubscriptionDe
 		return operation;
 	}
 
-	public IBaseResource getResource(IIdType payloadId, RequestPartitionId thePartitionId) throws ResourceGoneException {
+	public IBaseResource getResource(IIdType payloadId, RequestPartitionId thePartitionId, boolean theDeletedOK) throws ResourceGoneException {
 		RuntimeResourceDefinition resourceDef = myFhirContext.getResourceDefinition(payloadId.getResourceType());
 		SystemRequestDetails systemRequestDetails = new SystemRequestDetails().setRequestPartitionId(thePartitionId);
 		IFhirResourceDao<?> dao = myDaoRegistry.getResourceDao(resourceDef.getImplementingClass());
-		return dao.read(payloadId.toVersionless(),  systemRequestDetails);
+		return dao.read(payloadId.toVersionless(),  systemRequestDetails, theDeletedOK);
 	}
 
 
@@ -180,7 +181,8 @@ public class SubscriptionDeliveringRestHookSubscriber extends BaseSubscriptionDe
 
 			try {
 				if (payloadId != null) {
-					payloadResource = getResource(payloadId.toVersionless(), theMsg.getRequestPartitionId());
+					boolean deletedOK = theMsg.getOperationType() == BaseResourceModifiedMessage.OperationTypeEnum.DELETE;
+					payloadResource = getResource(payloadId.toVersionless(), theMsg.getRequestPartitionId(), deletedOK);
 				} else {
 					return null;
 				}

hapi-fhir-jpaserver-subscription/src/main/java/ca/uhn/fhir/jpa/subscription/match/matcher/subscriber/SubscriptionMatchingSubscriber.java

@@ -28,6 +28,7 @@ import org.springframework.messaging.MessagingException;
 import javax.annotation.Nonnull;
 import java.util.Collection;
 
+import static ca.uhn.fhir.rest.server.messaging.BaseResourceMessage.OperationTypeEnum.DELETE;
 import static org.apache.commons.lang3.ObjectUtils.defaultIfNull;
 import static org.apache.commons.lang3.StringUtils.isNotBlank;
 
@@ -91,8 +92,8 @@ public class SubscriptionMatchingSubscriber implements MessageHandler {
 			case CREATE:
 			case UPDATE:
 			case MANUALLY_TRIGGERED:
-				break;
 			case DELETE:
+				break;
 			default:
 				ourLog.trace("Not processing modified message for {}", theMsg.getOperationType());
 				// ignore anything else
@@ -143,6 +144,13 @@ public class SubscriptionMatchingSubscriber implements MessageHandler {
 				continue;
 			}
 
+			if (theMsg.getOperationType().equals(DELETE)) {
+				if (! nextActiveSubscription.getSubscription().getSendDeleteMessages()) {
+					ourLog.trace("Not processing modified message for {}", theMsg.getOperationType());
+					return;
+				}
+			}
+
 			InMemoryMatchResult matchResult;
 			if (nextActiveSubscription.getCriteria().getType() == SubscriptionCriteriaParser.TypeEnum.SEARCH_EXPRESSION) {
 				matchResult = mySubscriptionMatcher.match(nextActiveSubscription.getSubscription(), theMsg);
@@ -169,7 +177,11 @@ public class SubscriptionMatchingSubscriber implements MessageHandler {
 			ResourceDeliveryMessage deliveryMsg = new ResourceDeliveryMessage();
 			deliveryMsg.setPartitionId(theMsg.getPartitionId());
 
+			if (payload != null) {
 				deliveryMsg.setPayload(myFhirContext, payload, encoding);
+			} else {
+				deliveryMsg.setPayloadId(theMsg.getPayloadId(myFhirContext));
+			}
 			deliveryMsg.setSubscription(subscription);
 			deliveryMsg.setOperationType(theMsg.getOperationType());
 			deliveryMsg.setTransactionId(theMsg.getTransactionId());

hapi-fhir-jpaserver-subscription/src/test/java/ca/uhn/fhir/jpa/subscription/module/subscriber/SubscriptionMatchingSubscriberTest.java

@@ -1,24 +1,43 @@
 package ca.uhn.fhir.jpa.subscription.module.subscriber;
 
+import ca.uhn.fhir.interceptor.api.HookParams;
+import ca.uhn.fhir.interceptor.api.IInterceptorBroadcaster;
+import ca.uhn.fhir.interceptor.api.Pointcut;
 import ca.uhn.fhir.interceptor.model.RequestPartitionId;
 import ca.uhn.fhir.jpa.api.dao.IFhirResourceDao;
+import ca.uhn.fhir.jpa.subscription.match.matcher.subscriber.SubscriptionCriteriaParser;
+import ca.uhn.fhir.jpa.subscription.match.matcher.subscriber.SubscriptionMatchingSubscriber;
+import ca.uhn.fhir.jpa.subscription.match.registry.ActiveSubscription;
+import ca.uhn.fhir.jpa.subscription.match.registry.SubscriptionRegistry;
+import ca.uhn.fhir.jpa.subscription.model.CanonicalSubscription;
+import ca.uhn.fhir.jpa.subscription.model.ResourceModifiedMessage;
 import ca.uhn.fhir.jpa.subscription.module.standalone.BaseBlockingQueueSubscribableChannelDstu3Test;
+import ca.uhn.fhir.model.primitive.IdDt;
 import ca.uhn.fhir.rest.api.Constants;
+import ca.uhn.fhir.rest.server.messaging.BaseResourceModifiedMessage;
 import com.google.common.collect.Lists;
 import org.hl7.fhir.dstu3.model.Observation;
 import org.hl7.fhir.dstu3.model.Subscription;
 import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
+import org.mockito.Answers;
+import org.mockito.Mock;
 import org.mockito.Mockito;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import java.util.Collections;
 import java.util.List;
 
+import static ca.uhn.fhir.jpa.subscription.match.matcher.subscriber.SubscriptionCriteriaParser.TypeEnum.STARTYPE_EXPRESSION;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
 /**
  * Tests copied from jpa.subscription.resthook.RestHookTestDstu3Test
@@ -29,7 +48,7 @@ public class SubscriptionMatchingSubscriberTest extends BaseBlockingQueueSubscri
 
 	@BeforeEach
 	public void beforeEach() {
-		Mockito.when(myMockSubscriptionDao.getResourceType()).thenReturn(Subscription.class);
+		when(myMockSubscriptionDao.getResourceType()).thenReturn(Subscription.class);
 		myDaoRegistry.register(myMockSubscriptionDao);
 	}
 
@@ -264,11 +283,82 @@ public class SubscriptionMatchingSubscriberTest extends BaseBlockingQueueSubscri
 		mySubscriptionResourceNotMatched.awaitExpected();
 	}
 
+	@Nested
+	public class TestDeleteMessages {
+		private final SubscriptionMatchingSubscriber subscriber = new SubscriptionMatchingSubscriber();
+		@Mock ResourceModifiedMessage message;
+		@Mock IInterceptorBroadcaster myInterceptorBroadcaster;
+		@Mock SubscriptionRegistry mySubscriptionRegistry;
+		@Mock(answer = Answers.RETURNS_DEEP_STUBS) ActiveSubscription myActiveSubscription;
+		@Mock CanonicalSubscription myCanonicalSubscription;
+		@Mock SubscriptionCriteriaParser.SubscriptionCriteria mySubscriptionCriteria;
+
+		@Test
+		public void testAreNotIgnored()  {
+			ReflectionTestUtils.setField(subscriber, "myInterceptorBroadcaster", myInterceptorBroadcaster);
+			ReflectionTestUtils.setField(subscriber, "mySubscriptionRegistry", mySubscriptionRegistry);
+
+			when(message.getOperationType()).thenReturn(BaseResourceModifiedMessage.OperationTypeEnum.DELETE);
+			when(myInterceptorBroadcaster.callHooks(
+				eq(Pointcut.SUBSCRIPTION_BEFORE_PERSISTED_RESOURCE_CHECKED), any(HookParams.class))).thenReturn(true);
+			when(mySubscriptionRegistry.getAll()).thenReturn(Collections.emptyList());
+
+			subscriber.matchActiveSubscriptionsAndDeliver(message);
+
+			verify(myInterceptorBroadcaster).callHooks(
+				eq(Pointcut.SUBSCRIPTION_BEFORE_PERSISTED_RESOURCE_CHECKED), any(HookParams.class));
+			verify(myInterceptorBroadcaster).callHooks(
+				eq(Pointcut.SUBSCRIPTION_AFTER_PERSISTED_RESOURCE_CHECKED), any(HookParams.class));
+		}
+
+		@Test
+		public void matchActiveSubscriptionsChecksSendDeleteMessagesExtensionFlag() {
+			ReflectionTestUtils.setField(subscriber, "myInterceptorBroadcaster", myInterceptorBroadcaster);
+			ReflectionTestUtils.setField(subscriber, "mySubscriptionRegistry", mySubscriptionRegistry);
+
+			when(message.getOperationType()).thenReturn(BaseResourceModifiedMessage.OperationTypeEnum.DELETE);
+			when(myInterceptorBroadcaster.callHooks(
+				eq(Pointcut.SUBSCRIPTION_BEFORE_PERSISTED_RESOURCE_CHECKED), any(HookParams.class))).thenReturn(true);
+			when(message.getPayloadId(null)).thenReturn(new IdDt("Patient", 123L));
+			when(mySubscriptionRegistry.getAll()).thenReturn(Collections.singletonList(myActiveSubscription));
+			when(myActiveSubscription.getSubscription()).thenReturn(myCanonicalSubscription);
+			when(myActiveSubscription.getCriteria()).thenReturn(mySubscriptionCriteria);
+			when(myActiveSubscription.getId()).thenReturn("Patient/123");
+			when(mySubscriptionCriteria.getType()).thenReturn(STARTYPE_EXPRESSION);
+
+			subscriber.matchActiveSubscriptionsAndDeliver(message);
+
+			verify(myCanonicalSubscription, atLeastOnce()).getSendDeleteMessages();
+		}
+
+		@Test
+		public void matchActiveSubscriptionsAndDeliverSetsPartitionId() {
+			ReflectionTestUtils.setField(subscriber, "myInterceptorBroadcaster", myInterceptorBroadcaster);
+			ReflectionTestUtils.setField(subscriber, "mySubscriptionRegistry", mySubscriptionRegistry);
+
+			when(message.getOperationType()).thenReturn(BaseResourceModifiedMessage.OperationTypeEnum.DELETE);
+			when(myInterceptorBroadcaster.callHooks(
+				eq(Pointcut.SUBSCRIPTION_BEFORE_PERSISTED_RESOURCE_CHECKED), any(HookParams.class))).thenReturn(true);
+			when(message.getPayloadId(null)).thenReturn(new IdDt("Patient", 123L));
+			when(mySubscriptionRegistry.getAll()).thenReturn(Collections.singletonList(myActiveSubscription));
+			when(myActiveSubscription.getSubscription()).thenReturn(myCanonicalSubscription);
+			when(myActiveSubscription.getCriteria()).thenReturn(mySubscriptionCriteria);
+			when(myActiveSubscription.getId()).thenReturn("Patient/123");
+			when(mySubscriptionCriteria.getType()).thenReturn(STARTYPE_EXPRESSION);
+			when(myCanonicalSubscription.getSendDeleteMessages()).thenReturn(true);
+
+			subscriber.matchActiveSubscriptionsAndDeliver(message);
+
+			verify(message, atLeastOnce()).getPayloadId(null);
+		}
+	}
+
+
 
 	private void mockSubscriptionRead(RequestPartitionId theRequestPartitionId, Subscription subscription) {
 		Subscription modifiedSubscription = subscription.copy();
 		// the original partition info was the request info, but we need the actual storage partition.
 		modifiedSubscription.setUserData(Constants.RESOURCE_PARTITION_ID, theRequestPartitionId);
-		Mockito.when(myMockSubscriptionDao.read(eq(subscription.getIdElement()), any())).thenReturn(modifiedSubscription);
+		when(myMockSubscriptionDao.read(eq(subscription.getIdElement()), any())).thenReturn(modifiedSubscription);
 	}
 }

hapi-fhir-storage/src/main/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizer.java

@@ -38,6 +38,7 @@ import org.hl7.fhir.instance.model.api.IBaseMetaType;
 import org.hl7.fhir.instance.model.api.IBaseReference;
 import org.hl7.fhir.instance.model.api.IBaseResource;
 import org.hl7.fhir.instance.model.api.IPrimitiveType;
+import org.hl7.fhir.r4.model.BooleanType;
 import org.hl7.fhir.r4.model.Extension;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -50,6 +51,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import static ca.uhn.fhir.util.HapiExtensions.EX_SEND_DELETE_MESSAGES;
 import static java.util.stream.Collectors.mapping;
 import static java.util.stream.Collectors.toList;
 
@@ -268,6 +270,10 @@ public class SubscriptionCanonicalizer {
 			}
 		}
 
+		Extension extension = subscription.getExtensionByUrl(EX_SEND_DELETE_MESSAGES);
+		if (extension != null && extension.hasValue() && extension.getValue() instanceof BooleanType) {
+			retVal.setSendDeleteMessages(((BooleanType) extension.getValue()).booleanValue());
+		}
 		return retVal;
 	}
 

hapi-fhir-storage/src/main/java/ca/uhn/fhir/jpa/subscription/model/CanonicalSubscription.java

@@ -43,6 +43,7 @@ import java.util.Map;
 import static org.apache.commons.lang3.StringUtils.isNotBlank;
 
 public class CanonicalSubscription implements Serializable, Cloneable, IModelJson {
+
 	private static final long serialVersionUID = 1L;
 
 	@JsonProperty("id")
@@ -73,6 +74,8 @@ public class CanonicalSubscription implements Serializable, Cloneable, IModelJso
 	private String myPayloadSearchCriteria;
 	@JsonProperty("partitionId")
 	private Integer myPartitionId;
+	@JsonProperty("sendDeleteMessages")
+	private boolean mySendDeleteMessages;
 
 	/**
 	 * Constructor
@@ -90,7 +93,7 @@ public class CanonicalSubscription implements Serializable, Cloneable, IModelJso
 	}
 
 	/**
-	 * For now, we're using the R4 TriggerDefinition, but this
+	 * For now we're using the R4 TriggerDefinition, but this
 	 * may change in the future when things stabilize
 	 */
 	public void addTrigger(CanonicalEventDefinition theTrigger) {
@@ -237,13 +240,19 @@ public class CanonicalSubscription implements Serializable, Cloneable, IModelJso
 	}
 
 	/**
-	 * For now, we're using the R4 triggerdefinition, but this
+	 * For now we're using the R4 triggerdefinition, but this
 	 * may change in the future when things stabilize
 	 */
 	public CanonicalEventDefinition getTrigger() {
 		return myTrigger;
 	}
 
+	public boolean getSendDeleteMessages() { return mySendDeleteMessages; }
+
+	public void setSendDeleteMessages(boolean theSendDeleteMessages) {
+		mySendDeleteMessages = theSendDeleteMessages;
+	}
+
 	@Override
 	public boolean equals(Object theO) {
 		if (this == theO) return true;

hapi-fhir-storage/src/test/java/ca/uhn/fhir/jpa/subscription/match/registry/SubscriptionCanonicalizerTest.java

@@ -0,0 +1,42 @@
+package ca.uhn.fhir.jpa.subscription.match.registry;
+
+import ca.uhn.fhir.context.FhirContext;
+import ca.uhn.fhir.jpa.subscription.model.CanonicalSubscription;
+import org.hl7.fhir.r4.model.BooleanType;
+import org.hl7.fhir.r4.model.Extension;
+import org.hl7.fhir.r4.model.Subscription;
+import org.junit.jupiter.api.Test;
+
+import static ca.uhn.fhir.util.HapiExtensions.EX_SEND_DELETE_MESSAGES;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class SubscriptionCanonicalizerTest {
+
+	FhirContext r4Context = FhirContext.forR4();
+
+	private final SubscriptionCanonicalizer testedSC = new SubscriptionCanonicalizer(r4Context);
+
+	@Test
+	void testCanonicalizeR4SendDeleteMessagesSetsExtensionValueNotPresent() {
+		Subscription subscription = new Subscription();
+
+		CanonicalSubscription canonicalSubscription = testedSC.canonicalize(subscription);
+
+		assertFalse(canonicalSubscription.getSendDeleteMessages());
+	}
+
+
+	@Test
+	void testCanonicalizeR4SendDeleteMessagesSetsExtensionValue() {
+		Subscription subscription = new Subscription();
+		Extension sendDeleteMessagesExtension = new Extension()
+			.setUrl(EX_SEND_DELETE_MESSAGES)
+			.setValue(new BooleanType(true));
+		subscription.getExtension().add(sendDeleteMessagesExtension);
+
+		CanonicalSubscription canonicalSubscription = testedSC.canonicalize(subscription);
+
+		assertTrue(canonicalSubscription.getSendDeleteMessages());
+	}
+}

hapi-fhir-test-utilities/src/main/java/ca/uhn/fhir/test/utilities/server/HashMapResourceProviderExtension.java

@@ -89,12 +89,17 @@ public class HashMapResourceProviderExtension<T extends IBaseResource> extends H
 
 	public void waitForUpdateCount(long theCount) {
 		assertThat(theCount, greaterThanOrEqualTo(getCountUpdate()));
-		await().until(()->getCountUpdate(), equalTo(theCount));
+		await().until(this::getCountUpdate, equalTo(theCount));
 	}
 
 	public void waitForCreateCount(long theCount) {
 		assertThat(theCount, greaterThanOrEqualTo(getCountCreate()));
-		await().until(()->getCountCreate(), equalTo(theCount));
+		await().until(this::getCountCreate, equalTo(theCount));
+	}
+
+	public void waitForDeleteCount(long theCount) {
+		assertThat(theCount, greaterThanOrEqualTo(getCountDelete()));
+		await().until(this::getCountDelete, equalTo(theCount));
 	}
 
 	public List<T> getResourceUpdates() {