Checkstyle changes

* Upgrade to Checkstyle 9.0
* apply some JavaDocs rules
* Fix JavaDocs rules violations
* Some other minor clean up in the affected classes

spring-integration-jpa/src/main/java/org/springframework/integration/jpa/config/xml/JpaInboundChannelAdapterParser.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.
@@ -30,7 +30,7 @@ import org.springframework.integration.config.xml.IntegrationNamespaceUtils;
 import org.springframework.integration.jpa.inbound.JpaPollingChannelAdapter;
 
 /**
- * The JPA Inbound Channel adapter parser
+ * The JPA Inbound Channel adapter parser.
  *
  * @author Amol Nayak
  * @author Gunnar Hillert

spring-integration-jpa/src/main/java/org/springframework/integration/jpa/config/xml/JpaNamespaceHandler.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.
@@ -19,7 +19,7 @@ package org.springframework.integration.jpa.config.xml;
 import org.springframework.integration.config.xml.AbstractIntegrationNamespaceHandler;
 
 /**
- * The namespace handler for the JPA namespace
+ * The namespace handler for the JPA namespace.
  *
  * @author Amol Nayak
  * @author Gunnar Hillert

spring-integration-jpa/src/main/java/org/springframework/integration/jpa/config/xml/JpaOutboundChannelAdapterParser.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.
@@ -28,7 +28,7 @@ import org.springframework.integration.config.xml.IntegrationNamespaceUtils;
 import org.springframework.integration.jpa.outbound.JpaOutboundGatewayFactoryBean;
 
 /**
- * The parser for JPA outbound channel adapter
+ * The parser for JPA outbound channel adapter.
  *
  * @author Amol Nayak
  * @author Gunnar Hillert

spring-integration-jpa/src/main/java/org/springframework/integration/jpa/core/JpaExecutor.java

@@ -50,7 +50,7 @@ import org.springframework.util.CollectionUtils;
  *     <li>Sql Native Query</li>
  *     <li>JpQl Named Query</li>
  *     <li>Sql Native Named Query</li>
- * </ul>
+ * </ul>.
  *
  * When objects are being retrieved, it also possibly to:
  *
@@ -330,7 +330,7 @@ public class JpaExecutor implements InitializingBean, BeanFactoryAware {
 
 	/**
 	 * Set the expression that will be evaluated to get the {@code primaryKey} for
-	 * {@link javax.persistence.EntityManager#find(Class, Object)}
+	 * {@link javax.persistence.EntityManager#find(Class, Object)}.
 	 * @param idExpression the SpEL expression for entity {@code primaryKey}.
 	 * @since 4.0
 	 */

spring-integration-jpa/src/main/java/org/springframework/integration/jpa/core/JpaOperationFailedException.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.
@@ -17,10 +17,11 @@
 package org.springframework.integration.jpa.core;
 
 /**
- * An Exception that would be thrown if any of the Operations from {@link JpaOperations} fails
+ * An Exception that would be thrown if any of the Operations from {@link JpaOperations} fails.
  *
  * @author Amol Nayak
  * @author Gary Russell
+ *
  * @since 2.2
  *
  */

spring-integration-jpa/src/main/java/org/springframework/integration/jpa/core/JpaOperations.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.
@@ -122,7 +122,7 @@ public interface JpaOperations {
 			int maxNumberOfResults);
 
 	/**
-	 * Executes the provided query to return a list of results
+	 * Execute the provided query to return a list of results.
 	 * @param query The query.
 	 * @param source the Parameter source for this query to be executed, if none then set as null
 	 * @return The list of found entities.
@@ -140,7 +140,7 @@ public interface JpaOperations {
 	List<?> getResultListForQuery(String query, ParameterSource source, int firstResult, int maxNumberOfResults);
 
 	/**
-	 * Executes the provided query to return a single element
+	 * Execute the provided query to return a single element.
 	 * @param query Must not be empty
 	 * @param source the Parameter source for this query to be executed, if none then set as null
 	 * @return Will always return a result. If no object was found in the database an exception is raised.

spring-integration-jpa/src/main/java/org/springframework/integration/jpa/dsl/JpaRetrievingOutboundGatewaySpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 the original author or authors.
+ * Copyright 2016-2021 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.
@@ -81,7 +81,7 @@ public class JpaRetrievingOutboundGatewaySpec extends JpaBaseOutboundEndpointSpe
 
 	/**
 	 * Specify a SpEL expression that will be evaluated to get the {@code primaryKey} for
-	 * {@link javax.persistence.EntityManager#find(Class, Object)}
+	 * {@link javax.persistence.EntityManager#find(Class, Object)}.
 	 * @param idExpression the SpEL expression for entity {@code primaryKey}.
 	 * @return the spec
 	 */
@@ -91,7 +91,7 @@ public class JpaRetrievingOutboundGatewaySpec extends JpaBaseOutboundEndpointSpe
 
 	/**
 	 * Specify a SpEL expression that will be evaluated to get the {@code primaryKey} for
-	 * {@link javax.persistence.EntityManager#find(Class, Object)}
+	 * {@link javax.persistence.EntityManager#find(Class, Object)}.
 	 * @param idExpression the SpEL expression for entity {@code primaryKey}.
 	 * @return the spec
 	 */

spring-integration-jpa/src/main/java/org/springframework/integration/jpa/inbound/JpaPollingChannelAdapter.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.
@@ -29,7 +29,7 @@ import org.springframework.util.Assert;
  *     <li>Sql Native Query</li>
  *     <li>JpQl Named Query</li>
  *     <li>Sql Native Named Query</li>
- * </ul>
+ * </ul>.
  *
  * After the objects have been polled, it also possibly to either:
  *
@@ -64,7 +64,7 @@ public class JpaPollingChannelAdapter extends AbstractMessageSource<Object> {
 	}
 
 	/**
-	 * Check for mandatory attributes
+	 * Check for mandatory attributes.
 	 */
 	@Override
 	protected void onInit() {