Introduce a MessageGroup.condition (#3517)

* Introduce a `groupConditionSupplier` for MGS

* Add a `MessageGroup.condition` option
* Add a `MessageGroupStore.conditionSupplier` option
* Use it from the `SimpleMessageStore.addMessagesToGroup()` API
to populate `condition` (if any) into a `MessageGroup`
* Introduce a `GroupConditionProvider` contract to be implemented
on those `ReleaseStrategy` contracts which could be aware of group condition
* Populated a `GroupConditionProvider.getGroupConditionSupplier()`
into a `MessageGroupStore` from the `AbstractCorrelatingMessageHandler`
for end-user convenience
* Rework a `FileMarkerReleaseStrategy` to implement a `GroupConditionProvider`
to provide a function which produces a condition from `file_lineCount` header
of the `END` marker message
* Make the `FileMarkerReleaseStrategy` logic already based on the condition from a group
* Delegate `GroupConditionProvider` from the `FileAggregator`
* Add test for empty file aggregation

* * Implement `condition` in the `AbstractKeyValueMessageStore` and `MongoDbMessageStore`
* Test `condition` for `mongo-aggregator-config.xml` and `FileAggregatorTests` against GemFire

* * Implement `condition` in the `ConfigurableMongoDbMessageStore`

* * Implement `condition` in the `JdbcMessageStore`
* `FileAggregatorTests` against `JdbcMessageStore`
* Refactor `JdbcMessageStore` for better handling of message group metadata
* Remove unused `MARKED` column in the DDL in favor of newly introduced `CONDITION`

* * Add docs for message group condition

* * Move `conditionSupplier` option from MGS to AbstractCorrelatingMH
* Make it as a `BiFunction` to propagate existing condition alongside with the
message to consult
* Expose `groupConditionSupplier` in Java & XML DSLs

* * Fix language in docs

spring-integration-core/src/main/java/org/springframework/integration/aggregator/AbstractCorrelatingMessageHandler.java

@@ -27,6 +27,7 @@ import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.locks.Lock;
+import java.util.function.BiFunction;
 
 import org.aopalliance.aop.Advice;
 
@@ -158,6 +159,8 @@ public abstract class AbstractCorrelatingMessageHandler extends AbstractMessageP
 
 	private volatile boolean running;
 
+	private BiFunction<Message<?>, String, String> groupConditionSupplier;
+
 	public AbstractCorrelatingMessageHandler(MessageGroupProcessor processor, MessageGroupStore store,
 			CorrelationStrategy correlationStrategy, ReleaseStrategy releaseStrategy) {
 
@@ -361,6 +364,17 @@ public abstract class AbstractCorrelatingMessageHandler extends AbstractMessageP
 		this.expireDuration = expireDuration;
 	}
 
+	/**
+	 * Configure a {@link BiFunction} to supply a group condition from a message to be added to the group.
+	 * The {@code null} result from the function will reset a condition set before.
+	 * @param conditionSupplier the function to supply a group condition from a message to be added to the group.
+	 * @since 5.5
+	 * @see GroupConditionProvider
+	 */
+	public void setGroupConditionSupplier(BiFunction<Message<?>, String, String> conditionSupplier) {
+		this.groupConditionSupplier = conditionSupplier;
+	}
+
 	@Override
 	public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
 		this.applicationEventPublisher = applicationEventPublisher;
@@ -407,6 +421,10 @@ public abstract class AbstractCorrelatingMessageHandler extends AbstractMessageP
 		 */
 		this.lockRegistrySet = true;
 		this.forceReleaseProcessor = createGroupTimeoutProcessor();
+
+		if (this.releaseStrategy instanceof GroupConditionProvider) {
+			this.groupConditionSupplier = ((GroupConditionProvider) this.releaseStrategy).getGroupConditionSupplier();
+		}
 	}
 
 	private MessageGroupProcessor createGroupTimeoutProcessor() {
@@ -441,6 +459,11 @@ public abstract class AbstractCorrelatingMessageHandler extends AbstractMessageP
 		return this.releaseStrategy;
 	}
 
+	@Nullable
+	protected BiFunction<Message<?>, String, String> getGroupConditionSupplier() {
+		return this.groupConditionSupplier;
+	}
+
 	@Override
 	public MessageChannel getDiscardChannel() {
 		String channelName = this.discardChannelName;
@@ -542,6 +565,8 @@ public abstract class AbstractCorrelatingMessageHandler extends AbstractMessageP
 			this.logger.trace(() -> "Adding message to group [ " + messageGroupToLog + "]");
 			messageGroup = store(correlationKey, message);
 
+			setGroupConditionIfAny(message, messageGroup);
+
 			if (this.releaseStrategy.canRelease(messageGroup)) {
 				Collection<Message<?>> completedMessages = null;
 				try {
@@ -579,6 +604,14 @@ public abstract class AbstractCorrelatingMessageHandler extends AbstractMessageP
 		}
 	}
 
+	private void setGroupConditionIfAny(Message<?> message, MessageGroup messageGroup) {
+		if (this.groupConditionSupplier != null) {
+			String condition = this.groupConditionSupplier.apply(message, messageGroup.getCondition());
+			this.messageStore.setGroupCondition(messageGroup.getGroupId(), condition);
+			messageGroup.setCondition(condition);
+		}
+	}
+
 	protected boolean isExpireGroupsUponCompletion() {
 		return false;
 	}

spring-integration-core/src/main/java/org/springframework/integration/aggregator/GroupConditionProvider.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.aggregator;
+
+import java.util.function.BiFunction;
+
+import org.springframework.messaging.Message;
+
+/**
+ * A contract which can be implemented on the {@link ReleaseStrategy}
+ * and used in the {@link AbstractCorrelatingMessageHandler} to
+ * populate the provided group condition supplier.
+ *
+ * @author Artem Bilan
+ *
+ * @since 5.5
+ *
+ * @see AbstractCorrelatingMessageHandler#setGroupConditionSupplier(BiFunction)
+ */
+@FunctionalInterface
+public interface GroupConditionProvider {
+
+	BiFunction<Message<?>, String, String> getGroupConditionSupplier();
+
+}

spring-integration-core/src/main/java/org/springframework/integration/config/AggregatorFactoryBean.java

@@ -19,6 +19,7 @@ package org.springframework.integration.config;
 import java.time.Duration;
 import java.util.List;
 import java.util.Map;
+import java.util.function.BiFunction;
 import java.util.function.Function;
 
 import org.aopalliance.aop.Advice;
@@ -36,6 +37,7 @@ import org.springframework.integration.store.MessageGroup;
 import org.springframework.integration.store.MessageGroupStore;
 import org.springframework.integration.support.locks.LockRegistry;
 import org.springframework.integration.util.JavaUtils;
+import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.MessageHandler;
 import org.springframework.scheduling.TaskScheduler;
@@ -98,6 +100,8 @@ public class AggregatorFactoryBean extends AbstractSimpleMessageHandlerFactoryBe
 
 	private Function<MessageGroup, Map<String, Object>> headersFunction;
 
+	private BiFunction<Message<?>, String, String> groupConditionSupplier;
+
 	public void setProcessorBean(Object processorBean) {
 		this.processorBean = processorBean;
 	}
@@ -187,6 +191,10 @@ public class AggregatorFactoryBean extends AbstractSimpleMessageHandlerFactoryBe
 		this.expireDuration = expireDuration;
 	}
 
+	public void setGroupConditionSupplier(BiFunction<Message<?>, String, String> groupConditionSupplier) {
+		this.groupConditionSupplier = groupConditionSupplier;
+	}
+
 	@Override
 	protected AggregatingMessageHandler createHandler() {
 		MessageGroupProcessor outputProcessor;
@@ -233,6 +241,7 @@ public class AggregatorFactoryBean extends AbstractSimpleMessageHandlerFactoryBe
 				.acceptIfNotNull(this.releaseLockBeforeSend, aggregator::setReleaseLockBeforeSend)
 				.acceptIfNotNull(this.expireDuration,
 						(duration) -> aggregator.setExpireDuration(Duration.ofMillis(duration)))
+				.acceptIfNotNull(this.groupConditionSupplier, aggregator::setGroupConditionSupplier)
 				.acceptIfNotNull(this.expireTimeout, aggregator::setExpireTimeout);
 
 		return aggregator;

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractCorrelatingMessageHandlerParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -104,6 +104,8 @@ public abstract class AbstractCorrelatingMessageHandlerParser extends AbstractCo
 		IntegrationNamespaceUtils.setValueIfAttributeDefined(builder, element, "expire-timeout");
 		IntegrationNamespaceUtils.setValueIfAttributeDefined(builder, element, "expire-duration",
 				"expireDurationMillis");
+
+		IntegrationNamespaceUtils.setReferenceIfAttributeDefined(builder, element, "group-condition-supplier");
 	}
 
 }

spring-integration-core/src/main/java/org/springframework/integration/dsl/CorrelationHandlerSpec.java

@@ -20,6 +20,7 @@ import java.time.Duration;
 import java.util.Arrays;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.function.BiFunction;
 import java.util.function.Function;
 
 import org.aopalliance.aop.Advice;
@@ -36,6 +37,7 @@ import org.springframework.integration.expression.ValueExpression;
 import org.springframework.integration.store.MessageGroup;
 import org.springframework.integration.store.MessageGroupStore;
 import org.springframework.integration.support.locks.LockRegistry;
+import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageChannel;
 import org.springframework.scheduling.TaskScheduler;
 import org.springframework.util.Assert;
@@ -397,4 +399,15 @@ public abstract class CorrelationHandlerSpec<S extends CorrelationHandlerSpec<S,
 		return _this();
 	}
 
+	/**
+	 * Configure a {@link BiFunction} to supply a group condition from a message to be added to the group.
+	 * The {@code null} result from the function will reset a condition set before.
+	 * @param conditionSupplier the function to supply a group condition from a message to be added to the group.
+	 * @since 5.5
+	 */
+	public S groupConditionSupplier(BiFunction<Message<?>, String, String> conditionSupplier) {
+		this.handler.setGroupConditionSupplier(conditionSupplier);
+		return _this();
+	}
+
 }

spring-integration-core/src/main/java/org/springframework/integration/store/AbstractKeyValueMessageStore.java

@@ -180,6 +180,7 @@ public abstract class AbstractKeyValueMessageStore extends AbstractMessageGroupS
 					.create(this, groupId, metadata.getTimestamp(), metadata.isComplete());
 			messageGroup.setLastModified(metadata.getLastModified());
 			messageGroup.setLastReleasedMessageSequenceNumber(metadata.getLastReleasedMessageSequenceNumber());
+			messageGroup.setCondition(metadata.getCondition());
 			return messageGroup;
 		}
 		else {
@@ -294,6 +295,15 @@ public abstract class AbstractKeyValueMessageStore extends AbstractMessageGroupS
 		}
 	}
 
+	@Override
+	public void setGroupCondition(Object groupId, String condition) {
+		MessageGroupMetadata metadata = getGroupMetadata(groupId);
+		if (metadata != null) {
+			metadata.setCondition(condition);
+			doStore(this.groupPrefix + groupId, metadata);
+		}
+	}
+
 	@Override
 	public void setLastReleasedSequenceNumberForGroup(Object groupId, int sequenceNumber) {
 		Assert.notNull(groupId, GROUP_ID_MUST_NOT_BE_NULL);

spring-integration-core/src/main/java/org/springframework/integration/store/AbstractMessageGroupStore.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -47,10 +47,10 @@ public abstract class AbstractMessageGroupStore extends AbstractBatchingMessageG
 	private final MessageGroupFactory persistentMessageGroupFactory =
 			new SimpleMessageGroupFactory(SimpleMessageGroupFactory.GroupType.PERSISTENT);
 
-	private volatile boolean timeoutOnIdle;
-
 	private boolean lazyLoadMessageGroups = true;
 
+	private boolean timeoutOnIdle;
+
 	protected AbstractMessageGroupStore() {
 	}
 
@@ -111,7 +111,7 @@ public abstract class AbstractMessageGroupStore extends AbstractBatchingMessageG
 					this.expiryCallbacks.stream()
 							.anyMatch(UniqueExpiryCallback.class::isInstance);
 
-			if (uniqueExpiryCallbackPresent && this.logger.isErrorEnabled()) {
+			if (uniqueExpiryCallbackPresent) {
 				this.logger.error("Only one instance of 'UniqueExpiryCallback' can be registered in the " +
 						"'MessageGroupStore'. Use a separate 'MessageGroupStore' for each aggregator/resequencer.");
 			}

spring-integration-core/src/main/java/org/springframework/integration/store/MessageGroup.java

@@ -19,6 +19,7 @@ package org.springframework.integration.store;
 import java.util.Collection;
 import java.util.stream.Stream;
 
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
@@ -120,6 +121,21 @@ public interface MessageGroup {
 
 	void setLastModified(long lastModified);
 
+	/**
+	 * Add a condition statement to this group which can be consulted later on, e.g. from the release strategy.
+	 * @param condition statement which could be consulted later on, e.g. from the release strategy.
+	 * @since 5.5
+	 */
+	void setCondition(String condition);
+
+	/**
+	 * Return the condition for this group to consult with, e.g. from the release strategy.
+	 * @return the condition for this group to consult with, e.g. from the release strategy.
+	 * @since 5.5
+	 */
+	@Nullable
+	String getCondition();
+
 	void clear();
 
 }

spring-integration-core/src/main/java/org/springframework/integration/store/MessageGroupMetadata.java

@@ -50,6 +50,8 @@ public class MessageGroupMetadata implements Serializable {
 
 	private volatile int lastReleasedMessageSequenceNumber;
 
+	private volatile String condition;
+
 	private MessageGroupMetadata() {
 		//For Jackson deserialization
 	}
@@ -129,4 +131,12 @@ public class MessageGroupMetadata implements Serializable {
 		this.lastReleasedMessageSequenceNumber = lastReleasedMessageSequenceNumber;
 	}
 
+	public String getCondition() {
+		return this.condition;
+	}
+
+	public void setCondition(String condition) {
+		this.condition = condition;
+	}
+
 }

spring-integration-core/src/main/java/org/springframework/integration/store/MessageGroupStore.java

@@ -96,6 +96,17 @@ public interface MessageGroupStore extends BasicMessageGroupStore {
 	 */
 	void setLastReleasedSequenceNumberForGroup(Object groupId, int sequenceNumber);
 
+	/**
+	 * Add a condition sentence into the group.
+	 * Can be used later on for making some decisions for group, e.g. release strategy
+	 * for correlation handler can consult this condition instead of iterating all
+	 * the messages in group.
+	 * @param groupId The group identifier.
+	 * @param condition The condition to store into the group.
+	 * @since 5.5
+	 */
+	void setGroupCondition(Object groupId, String condition);
+
 	/**
 	 * @return The iterator of currently accumulated {@link MessageGroup}s.
 	 */

spring-integration-core/src/main/java/org/springframework/integration/store/PersistentMessageGroup.java

@@ -27,6 +27,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.integration.IntegrationMessageHeaderAccessor;
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
@@ -175,6 +176,17 @@ class PersistentMessageGroup implements MessageGroup {
 		this.original.setLastReleasedMessageSequenceNumber(sequenceNumber);
 	}
 
+	@Override
+	public void setCondition(String condition) {
+		this.original.setCondition(condition);
+	}
+
+	@Override
+	@Nullable
+	public String getCondition() {
+		return this.original.getCondition();
+	}
+
 	@Override
 	public void clear() {
 		this.original.clear();

spring-integration-core/src/main/java/org/springframework/integration/store/SimpleMessageGroup.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,12 +24,13 @@ import java.util.LinkedHashSet;
 import java.util.Set;
 
 import org.springframework.integration.IntegrationMessageHeaderAccessor;
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
 
 /**
  * Represents a mutable group of correlated messages that is bound to a certain {@link MessageStore} and group id.
- * The group will grow during its lifetime, when messages are <code>add</code>ed to it.
+ * The group will grow during its lifetime, when messages are {@link #add}ed to it.
  * This MessageGroup is thread safe.
  *
  * @author Iwein Fuld
@@ -56,8 +57,11 @@ public class SimpleMessageGroup implements MessageGroup {
 
 	private volatile boolean complete;
 
+	@Nullable
+	private volatile String condition;
+
 	public SimpleMessageGroup(Object groupId) {
-		this(Collections.<Message<?>>emptyList(), groupId);
+		this(Collections.emptyList(), groupId);
 	}
 
 	public SimpleMessageGroup(Collection<? extends Message<?>> messages, Object groupId) {
@@ -172,6 +176,17 @@ public class SimpleMessageGroup implements MessageGroup {
 		return this.messages.size();
 	}
 
+	@Override
+	public void setCondition(String condition) {
+		this.condition = condition;
+	}
+
+	@Override
+	@Nullable
+	public String getCondition() {
+		return this.condition;
+	}
+
 	@Override
 	public Message<?> getOne() {
 		synchronized (this.messages) {

spring-integration-core/src/main/java/org/springframework/integration/store/SimpleMessageStore.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,12 +56,11 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 
 	private static final String INTERRUPTED_WHILE_OBTAINING_LOCK = "Interrupted while obtaining lock";
 
-	private final ConcurrentMap<UUID, Message<?>> idToMessage = new ConcurrentHashMap<UUID, Message<?>>();
+	private final ConcurrentMap<UUID, Message<?>> idToMessage = new ConcurrentHashMap<>();
 
-	private final ConcurrentMap<Object, MessageGroup> groupIdToMessageGroup =
-			new ConcurrentHashMap<Object, MessageGroup>();
+	private final ConcurrentMap<Object, MessageGroup> groupIdToMessageGroup = new ConcurrentHashMap<>();
 
-	private final ConcurrentMap<Object, UpperBound> groupToUpperBound = new ConcurrentHashMap<Object, UpperBound>();
+	private final ConcurrentMap<Object, UpperBound> groupToUpperBound = new ConcurrentHashMap<>();
 
 	private final int groupCapacity;
 
@@ -69,14 +68,14 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 
 	private final UpperBound individualUpperBound;
 
-	private volatile LockRegistry lockRegistry;
+	private final long upperBoundTimeout;
+
+	private LockRegistry lockRegistry;
+
+	private boolean copyOnGet = false;
 
 	private volatile boolean isUsed;
 
-	private volatile boolean copyOnGet = false;
-
-	private final long upperBoundTimeout;
-
 	/**
 	 * Creates a SimpleMessageStore with a maximum size limited by the given capacity, or unlimited size if the given
 	 * capacity is less than 1. The capacities are applied independently to messages stored via
@@ -183,7 +182,7 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 	public <T> Message<T> addMessage(Message<T> message) {
 		this.isUsed = true;
 		if (!this.individualUpperBound.tryAcquire(this.upperBoundTimeout)) {
-			throw new MessagingException(this.getClass().getSimpleName()
+			throw new MessagingException(getClass().getSimpleName()
 					+ " was out of capacity ("
 					+ this.individualCapacity
 					+ "), try constructing it with a larger capacity.");
@@ -254,6 +253,7 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 						.create(group.getMessages(), groupId, group.getTimestamp(), group.isComplete());
 				simpleMessageGroup.setLastModified(group.getLastModified());
 				simpleMessageGroup.setLastReleasedMessageSequenceNumber(group.getLastReleasedMessageSequenceNumber());
+				simpleMessageGroup.setCondition(group.getCondition());
 				return simpleMessageGroup;
 			}
 			finally {
@@ -353,8 +353,9 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 			lock.lockInterruptibly();
 			try {
 				MessageGroup group = this.groupIdToMessageGroup.get(groupId);
-				Assert.notNull(group, MESSAGE_GROUP_FOR_GROUP_ID + groupId + "' " +
-						"can not be located while attempting to remove Message(s) from the MessageGroup");
+				Assert.notNull(group,
+						() -> MESSAGE_GROUP_FOR_GROUP_ID + groupId + "' " +
+								"can not be located while attempting to remove Message(s) from the MessageGroup");
 				UpperBound upperBound = this.groupToUpperBound.get(groupId);
 				Assert.state(upperBound != null, UPPER_BOUND_MUST_NOT_BE_NULL);
 				boolean modified = false;
@@ -380,7 +381,15 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 
 	@Override
 	public Iterator<MessageGroup> iterator() {
-		return new HashSet<MessageGroup>(this.groupIdToMessageGroup.values()).iterator();
+		return new HashSet<>(this.groupIdToMessageGroup.values()).iterator();
+	}
+
+	@Override
+	public void setGroupCondition(Object groupId, String condition) {
+		MessageGroup group = this.groupIdToMessageGroup.get(groupId);
+		if (group != null) {
+			group.setCondition(condition);
+		}
 	}
 
 	@Override
@@ -390,8 +399,9 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 			lock.lockInterruptibly();
 			try {
 				MessageGroup group = this.groupIdToMessageGroup.get(groupId);
-				Assert.notNull(group, MESSAGE_GROUP_FOR_GROUP_ID + groupId + "' " +
-						"can not be located while attempting to set 'lastReleasedSequenceNumber'");
+				Assert.notNull(group,
+						() -> MESSAGE_GROUP_FOR_GROUP_ID + groupId + "' " +
+								"can not be located while attempting to set 'lastReleasedSequenceNumber'");
 				group.setLastReleasedMessageSequenceNumber(sequenceNumber);
 				group.setLastModified(System.currentTimeMillis());
 			}
@@ -412,8 +422,9 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 			lock.lockInterruptibly();
 			try {
 				MessageGroup group = this.groupIdToMessageGroup.get(groupId);
-				Assert.notNull(group, MESSAGE_GROUP_FOR_GROUP_ID + groupId + "' " +
-						"can not be located while attempting to complete the MessageGroup");
+				Assert.notNull(group,
+						() -> MESSAGE_GROUP_FOR_GROUP_ID + groupId + "' " +
+								"can not be located while attempting to complete the MessageGroup");
 				group.complete();
 				group.setLastModified(System.currentTimeMillis());
 			}
@@ -466,8 +477,9 @@ public class SimpleMessageStore extends AbstractMessageGroupStore
 			lock.lockInterruptibly();
 			try {
 				MessageGroup group = this.groupIdToMessageGroup.get(groupId);
-				Assert.notNull(group, MESSAGE_GROUP_FOR_GROUP_ID + groupId + "' " +
-						"can not be located while attempting to complete the MessageGroup");
+				Assert.notNull(group,
+						() -> MESSAGE_GROUP_FOR_GROUP_ID + groupId + "' " +
+								"can not be located while attempting to complete the MessageGroup");
 				group.clear();
 				group.setLastModified(System.currentTimeMillis());
 				UpperBound upperBound = this.groupToUpperBound.get(groupId);

spring-integration-core/src/main/resources/org/springframework/integration/config/spring-integration.xsd

@@ -4071,6 +4071,19 @@
 						</xsd:documentation>
 					</xsd:annotation>
 				</xsd:attribute>
+				<xsd:attribute name="group-condition-supplier" type="xsd:string">
+					<xsd:annotation>
+						<xsd:appinfo>
+							<tool:annotation kind="ref">
+								<tool:expected-type type="java.util.function.BiFunction"/>
+							</tool:annotation>
+						</xsd:appinfo>
+						<xsd:documentation>
+							A reference to a 'java.util.function.BiFunction' bean that may provide a group
+							condition evaluated against the message to be added to the group.
+						</xsd:documentation>
+					</xsd:annotation>
+				</xsd:attribute>
 			</xsd:extension>
 		</xsd:complexContent>
 	</xsd:complexType>