Apply Nullability for Zip module

Related to: #10083

* Add `@org.jspecify.annotations.NullMarked` into all the `package-info.java` of Zip module packages
* Fix reported problems

Author: artembilan

spring-integration-zip/src/main/java/org/springframework/integration/zip/config/xml/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides parser classes to provide Xml namespace support for the Zip components.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.zip.config.xml;

spring-integration-zip/src/main/java/org/springframework/integration/zip/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Root package of the Zip Module.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.zip;

spring-integration-zip/src/main/java/org/springframework/integration/zip/splitter/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Classes to support Splitter pattern for Zip.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.zip.splitter;

spring-integration-zip/src/main/java/org/springframework/integration/zip/transformer/AbstractZipTransformer.java

@@ -19,6 +19,8 @@
 import java.io.File;
 import java.nio.charset.Charset;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.integration.transformer.AbstractTransformer;
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
@@ -93,7 +95,7 @@ protected void onInit() {
 	 * @param message the message and its payload must not be null.
 	 */
 	@Override
-	protected Object doTransform(Message<?> message) {
+	protected @Nullable Object doTransform(Message<?> message) {
 		return doZipTransform(message);
 	}
 
@@ -103,6 +105,6 @@ protected Object doTransform(Message<?> message) {
 	 * @param message The message will never be null.
 	 * @return The result of the Zip transformation.
 	 */
-	protected abstract Object doZipTransform(Message<?> message);
+	protected abstract @Nullable Object doZipTransform(Message<?> message);
 
 }

spring-integration-zip/src/main/java/org/springframework/integration/zip/transformer/UnZipTransformer.java

@@ -25,15 +25,18 @@
 import java.io.UncheckedIOException;
 import java.util.SortedMap;
 import java.util.TreeMap;
+import java.util.UUID;
 import java.util.zip.ZipEntry;
 
 import org.apache.commons.io.IOUtils;
+import org.jspecify.annotations.Nullable;
 import org.zeroturnaround.zip.ZipEntryCallback;
 import org.zeroturnaround.zip.ZipException;
 import org.zeroturnaround.zip.ZipUtil;
 
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
+import org.springframework.util.Assert;
 
 /**
  * Transformer implementation that applies an UnZip transformation to the message
@@ -68,7 +71,7 @@ public void setExpectSingleResult(boolean expectSingleResult) {
 	}
 
 	@Override
-	protected Object doZipTransform(final Message<?> message) {
+	protected @Nullable Object doZipTransform(final Message<?> message) {
 		Object payload = message.getPayload();
 		Object unzippedData;
 
@@ -100,6 +103,10 @@ else if (payload instanceof byte[] bytes) {
 
 			final SortedMap<String, Object> uncompressedData = new TreeMap<>();
 
+			UUID messageId = message.getHeaders().getId();
+			Assert.state(messageId != null,
+					() -> "The 'MessageHeaders.ID' must be provided in request message: " + message);
+
 			ZipUtil.iterate(inputStream, new ZipEntryCallback() {
 
 				@Override
@@ -115,7 +122,7 @@ public void process(InputStream zipEntryInputStream, ZipEntry zipEntry) throws I
 							zipEntryName, zipEntryTime, zipEntryCompressedSize, type));
 
 					if (ZipResultType.FILE.equals(zipResultType)) {
-						final File destinationFile = checkPath(message, zipEntryName);
+						final File destinationFile = checkPath(messageId, zipEntryName);
 
 						if (zipEntry.isDirectory()) {
 							destinationFile.mkdirs(); //NOSONAR false positive
@@ -128,7 +135,7 @@ public void process(InputStream zipEntryInputStream, ZipEntry zipEntry) throws I
 					}
 					else if (ZipResultType.BYTE_ARRAY.equals(zipResultType)) {
 						if (!zipEntry.isDirectory()) {
-							checkPath(message, zipEntryName);
+							checkPath(messageId, zipEntryName);
 							byte[] data = IOUtils.toByteArray(zipEntryInputStream);
 							uncompressedData.put(zipEntryName, data);
 						}
@@ -138,8 +145,8 @@ else if (ZipResultType.BYTE_ARRAY.equals(zipResultType)) {
 					}
 				}
 
-				public File checkPath(final Message<?> message, final String zipEntryName) throws IOException {
-					File tempDir = new File(workDirectory, message.getHeaders().getId().toString()); // NOSONAR
+				public File checkPath(UUID messageId, final String zipEntryName) throws IOException {
+					File tempDir = new File(workDirectory, messageId.toString());
 					tempDir.mkdirs(); //NOSONAR false positive
 					final File destinationFile = new File(tempDir, zipEntryName);
 
@@ -157,7 +164,7 @@ public File checkPath(final Message<?> message, final String zipEntryName) throw
 			});
 
 			if (uncompressedData.isEmpty()) {
-				logger.warn(() -> "No data unzipped from payload with message Id " + message.getHeaders().getId());
+				logger.warn(() -> "No data unzipped from payload with message Id " + messageId);
 				unzippedData = null;
 			}
 			else {
@@ -169,8 +176,7 @@ public File checkPath(final Message<?> message, final String zipEntryName) throw
 					else {
 						throw new MessagingException(message,
 								String.format("The UnZip operation extracted %s "
-										+ "result objects but expectSingleResult was 'true'.", uncompressedData
-										.size()));
+										+ "result objects but expectSingleResult was 'true'.", uncompressedData.size()));
 					}
 				}
 				else {

spring-integration-zip/src/main/java/org/springframework/integration/zip/transformer/ZipTransformer.java

@@ -60,6 +60,7 @@ public class ZipTransformer extends AbstractZipTransformer {
 
 	private boolean useFileAttributes = true;
 
+	@SuppressWarnings("NullAway.Init")
 	private FileNameGenerator fileNameGenerator;
 
 	/**
@@ -214,22 +215,18 @@ private ZipEntrySource createZipEntrySource(Object item,
 		if (item instanceof final File filePayload) {
 			String fileName = useFileAttributes ? filePayload.getName() : zipEntryName;
 
-			if (((File) item).isDirectory()) {
+			if (filePayload.isDirectory()) {
 				throw new UnsupportedOperationException("Zipping of directories is not supported.");
 			}
 
 			return new FileSource(fileName, filePayload);
 
 		}
 		else if (item instanceof byte[] || item instanceof String) {
-			byte[] bytesToCompress;
-
-			if (item instanceof String) {
-				bytesToCompress = ((String) item).getBytes(this.charset);
-			}
-			else {
-				bytesToCompress = (byte[]) item;
-			}
+			byte[] bytesToCompress =
+					item instanceof String stringItem
+							? stringItem.getBytes(this.charset)
+							: (byte[]) item;
 
 			return new ByteSource(zipEntryName, bytesToCompress, lastModifiedDate.getTime());
 		}

spring-integration-zip/src/main/java/org/springframework/integration/zip/transformer/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Classes to support Transformer pattern for Zip.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.zip.transformer;