feat(storage): update compose sample to support deleteSourceObjects option (#13493)

Update composeObject snippet to support deleteSourceObjects option.
Add corresponding system integration tests.

[Generated-by: AI]

Co-authored-by: Dhriti07 <56169283+Dhriti07@users.noreply.github.com>

Author: nidhiii-27

java-storage/samples/snippets/src/main/java/com/example/storage/object/ComposeObject.java

@@ -28,7 +28,8 @@ public static void composeObject(
       String firstObjectName,
       String secondObjectName,
       String targetObjectName,
-      String projectId) {
+      String projectId,
+      boolean deleteSourceObjects) {
     // The ID of your GCP project
     // String projectId = "your-project-id";
 
@@ -70,17 +71,20 @@ public static void composeObject(
             .addSource(firstObjectName, secondObjectName)
             .setTarget(BlobInfo.newBuilder(bucketName, targetObjectName).build())
             .setTargetOptions(precondition)
+            .setDeleteSourceObjects(deleteSourceObjects)
             .build();
 
     Blob compositeObject = storage.compose(composeRequest);
 
+    String deletionMessage = deleteSourceObjects ? " and the source objects were deleted." : ".";
     System.out.println(
         "New composite object "
             + compositeObject.getName()
             + " was created by combining "
             + firstObjectName
             + " and "
-            + secondObjectName);
+            + secondObjectName
+            + deletionMessage);
   }
 }
 // [END storage_compose_file]

java-storage/samples/snippets/src/test/java/com/example/storage/ITObjectSnippets.java

@@ -468,12 +468,39 @@ public void testComposeObject() {
         BlobInfo.newBuilder(bucket.getName(), secondObject).build(), secondObject.getBytes(UTF_8));
 
     ComposeObject.composeObject(
-        bucket.getName(), firstObject, secondObject, targetObject, GOOGLE_CLOUD_PROJECT);
+        bucket.getName(), firstObject, secondObject, targetObject, GOOGLE_CLOUD_PROJECT, false);
 
     String got = stdOut.getCapturedOutputAsUtf8String();
     assertThat(got).contains(firstObject);
     assertThat(got).contains(secondObject);
     assertThat(got).contains(targetObject);
+    // Verify source objects still exist
+    assertThat(storage.get(bucket.getName(), firstObject)).isNotNull();
+    assertThat(storage.get(bucket.getName(), secondObject)).isNotNull();
+  }
+
+  @Test
+  public void testComposeObjectWithDeleteSources() {
+    String firstObject = generator.randomObjectName();
+    String secondObject = generator.randomObjectName();
+    String targetObject = generator.randomObjectName();
+    storage.create(
+        BlobInfo.newBuilder(bucket.getName(), firstObject).build(), firstObject.getBytes(UTF_8));
+    storage.create(
+        BlobInfo.newBuilder(bucket.getName(), secondObject).build(), secondObject.getBytes(UTF_8));
+
+    ComposeObject.composeObject(
+        bucket.getName(), firstObject, secondObject, targetObject, GOOGLE_CLOUD_PROJECT, true);
+
+    String got = stdOut.getCapturedOutputAsUtf8String();
+    assertThat(got).contains(firstObject);
+    assertThat(got).contains(secondObject);
+    assertThat(got).contains(targetObject);
+    assertThat(got).contains("and the source objects were deleted");
+
+    // Verify source objects are deleted
+    assertThat(storage.get(bucket.getName(), firstObject)).isNull();
+    assertThat(storage.get(bucket.getName(), secondObject)).isNull();
   }
 
   @Test