Harmonize packages in file module

* Move inbound channel adapters into a new `inbound` package
* Move outbound channel adapters into a new `outbound` package
* Preserve existing classes in the root package as deprecated
and as extensions of new classes
* Some tests refactoring (affected files) according to modern AssertJ API

Author: artembilan

spring-integration-file/src/main/java/org/springframework/integration/file/FileReadingMessageSource.java

@@ -26,9 +26,9 @@
 import org.springframework.beans.factory.BeanNameAware;
 import org.springframework.beans.factory.config.AbstractFactoryBean;
 import org.springframework.integration.file.DirectoryScanner;
-import org.springframework.integration.file.FileReadingMessageSource;
 import org.springframework.integration.file.filters.CompositeFileListFilter;
 import org.springframework.integration.file.filters.FileListFilter;
+import org.springframework.integration.file.inbound.FileReadingMessageSource;
 import org.springframework.integration.file.locking.AbstractFileLockerFilter;
 import org.springframework.util.Assert;
 

spring-integration-file/src/main/java/org/springframework/integration/file/FileWritingMessageHandler.java

@@ -23,12 +23,13 @@
 import org.springframework.integration.config.ExpressionFactoryBean;
 import org.springframework.integration.config.xml.IntegrationNamespaceUtils;
 import org.springframework.integration.file.DefaultFileNameGenerator;
+import org.springframework.integration.file.outbound.FileWritingMessageHandler;
 import org.springframework.util.StringUtils;
 
 /**
  * A common helper class for the 'outbound-channel-adapter' and 'outbound-gateway'
  * element parsers. Both of those are responsible for creating an instance of
- * {@link org.springframework.integration.file.FileWritingMessageHandler}.
+ * {@link FileWritingMessageHandler}.
  *
  * @author Mark Fisher
  * @author Artem Bilan

spring-integration-file/src/main/java/org/springframework/integration/file/config/FileReadingMessageSourceFactoryBean.java

@@ -24,8 +24,8 @@
 import org.springframework.integration.JavaUtils;
 import org.springframework.integration.config.AbstractSimpleMessageHandlerFactoryBean;
 import org.springframework.integration.file.FileNameGenerator;
-import org.springframework.integration.file.FileWritingMessageHandler;
-import org.springframework.integration.file.FileWritingMessageHandler.MessageFlushPredicate;
+import org.springframework.integration.file.outbound.FileWritingMessageHandler;
+import org.springframework.integration.file.outbound.FileWritingMessageHandler.MessageFlushPredicate;
 import org.springframework.integration.file.support.FileExistsMode;
 
 /**

spring-integration-file/src/main/java/org/springframework/integration/file/config/FileWritingMessageHandlerBeanDefinitionBuilder.java

@@ -32,11 +32,11 @@
 import org.springframework.integration.expression.FunctionExpression;
 import org.springframework.integration.file.DirectoryScanner;
 import org.springframework.integration.file.FileLocker;
-import org.springframework.integration.file.FileReadingMessageSource;
 import org.springframework.integration.file.RecursiveDirectoryScanner;
 import org.springframework.integration.file.config.FileListFilterFactoryBean;
 import org.springframework.integration.file.filters.ExpressionFileListFilter;
 import org.springframework.integration.file.filters.FileListFilter;
+import org.springframework.integration.file.inbound.FileReadingMessageSource;
 import org.springframework.integration.file.locking.NioFileLocker;
 import org.springframework.util.Assert;
 
@@ -224,7 +224,7 @@ public FileInboundChannelAdapterSpec regexFilter(String regex) {
 	 */
 	public FileInboundChannelAdapterSpec locker(FileLocker locker) {
 		Assert.isNull(this.locker,
-				"The 'locker' (" + this.locker + ") is already configured for the FileReadingMessageSource");
+				() -> "The 'locker' (" + this.locker + ") is already configured for the FileReadingMessageSource");
 		this.locker = locker;
 		this.target.setLocker(locker);
 		this.filtersSet = true;

spring-integration-file/src/main/java/org/springframework/integration/file/config/FileWritingMessageHandlerFactoryBean.java

@@ -29,7 +29,7 @@
 import org.springframework.integration.expression.FunctionExpression;
 import org.springframework.integration.file.DefaultFileNameGenerator;
 import org.springframework.integration.file.FileNameGenerator;
-import org.springframework.integration.file.FileWritingMessageHandler;
+import org.springframework.integration.file.outbound.FileWritingMessageHandler;
 import org.springframework.integration.file.support.FileExistsMode;
 import org.springframework.messaging.Message;
 import org.springframework.scheduling.TaskScheduler;

spring-integration-file/src/main/java/org/springframework/integration/file/dsl/FileInboundChannelAdapterSpec.java

@@ -31,6 +31,7 @@
 import org.springframework.integration.file.DirectoryScanner;
 import org.springframework.integration.file.filters.ExpressionFileListFilter;
 import org.springframework.integration.file.filters.FileListFilter;
+import org.springframework.integration.file.inbound.FileReadingMessageSource;
 import org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer;
 import org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizingMessageSource;
 import org.springframework.integration.metadata.MetadataStore;
@@ -181,7 +182,7 @@ public S filter(FileListFilter<F> filter) {
 	 * Configure the {@link ExpressionFileListFilter}.
 	 * @param expression the SpEL expression for files filtering.
 	 * @return the spec.
-	 * @see org.springframework.integration.file.FileReadingMessageSource#setFilter(FileListFilter)
+	 * @see FileReadingMessageSource#setFilter(FileListFilter)
 	 * @see ExpressionFileListFilter
 	 */
 	public S filterExpression(String expression) {
@@ -193,7 +194,7 @@ public S filterExpression(String expression) {
 	 * Configure the {@link ExpressionFileListFilter}.
 	 * @param filterFunction the {@link Function} for files filtering.
 	 * @return the spec.
-	 * @see org.springframework.integration.file.FileReadingMessageSource#setFilter(FileListFilter)
+	 * @see FileReadingMessageSource#setFilter(FileListFilter)
 	 * @see ExpressionFileListFilter
 	 */
 	public S filterFunction(Function<F, Boolean> filterFunction) {

spring-integration-file/src/main/java/org/springframework/integration/file/dsl/FileWritingMessageHandlerSpec.java

@@ -26,10 +26,12 @@
 
 import org.jspecify.annotations.Nullable;
 
+import org.springframework.integration.file.inbound.FileReadingMessageSource;
+
 /**
  * {@link FileListFilter} that passes files only one time. This can
  * conveniently be used to prevent duplication of files, as is done in
- * {@link org.springframework.integration.file.FileReadingMessageSource}.
+ * {@link FileReadingMessageSource}.
  * <p>
  * This implementation is thread safe.
  *