chore: make ParallelCompositeUploadException public (#2245)

Tweak public api to be List vs ImmutableList so we are not hard coded against guava.

google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadException.java

@@ -21,28 +21,42 @@
 import com.google.api.gax.rpc.ApiException;
 import com.google.api.gax.rpc.ErrorDetails;
 import com.google.api.gax.rpc.StatusCode;
-import com.google.common.collect.ImmutableList;
 import io.grpc.Status.Code;
+import java.util.List;
 
-final class ParallelCompositeUploadException extends ApiException {
+/**
+ * An exception which provides access to created objects during a Parallel Composite Upload that did
+ * not finish successfully.
+ *
+ * <p>This exception can occur when calling any method on the {@link
+ * java.nio.channels.WritableByteChannel} returned from {@link BlobWriteSession#open()}, in which
+ * case it will be the cause of a {@link StorageException}.
+ *
+ * <p>Similarly, this exception will be the cause of a {@link
+ * java.util.concurrent.CancellationException} thrown by the {@link BlobWriteSession#getResult()}.
+ */
+public final class ParallelCompositeUploadException extends ApiException {
 
-  private final ApiFuture<ImmutableList<BlobId>> createdObjects;
+  private final ApiFuture<List<BlobId>> createdObjects;
 
   private ParallelCompositeUploadException(
       Throwable cause,
       StatusCode statusCode,
       ErrorDetails errorDetails,
-      ApiFuture<ImmutableList<BlobId>> createdObjects) {
+      ApiFuture<List<BlobId>> createdObjects) {
     super(cause, statusCode, false, errorDetails);
     this.createdObjects = createdObjects;
   }
 
-  public ApiFuture<ImmutableList<BlobId>> getCreatedObjects() {
+  /**
+   * A future list of the {@link BlobId}s which were created during the Parallel Composite Upload
+   * but may not have successfully been cleaned up.
+   */
+  public ApiFuture<List<BlobId>> getCreatedObjects() {
     return createdObjects;
   }
 
-  static ParallelCompositeUploadException of(
-      Throwable t, ApiFuture<ImmutableList<BlobId>> createdObjects) {
+  static ParallelCompositeUploadException of(Throwable t, ApiFuture<List<BlobId>> createdObjects) {
     StatusCode statusCode;
     ErrorDetails errorDetails;
 

google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannel.java

@@ -431,7 +431,7 @@ private BlobInfo definePart(BlobInfo ultimateObject, PartRange partRange, long o
   }
 
   private <R> ApiFuture<R> asyncCleanupAfterFailure(Throwable originalFailure) {
-    ApiFuture<ImmutableList<BlobId>> pendingAndSuccessfulBlobIds =
+    ApiFuture<List<BlobId>> pendingAndSuccessfulBlobIds =
         getPendingAndSuccessfulBlobIds(exec, pendingParts, successfulParts);
     return ApiFutures.transformAsync(
         pendingAndSuccessfulBlobIds,
@@ -558,21 +558,21 @@ static ParallelCompositeUploadException buildParallelCompositeUploadException(
       Executor exec,
       List<ApiFuture<BlobInfo>> pendingParts,
       List<BlobId> successfulParts) {
-    ApiFuture<ImmutableList<BlobId>> fCreatedObjects =
+    ApiFuture<List<BlobId>> fCreatedObjects =
         getPendingAndSuccessfulBlobIds(exec, pendingParts, successfulParts);
 
     return ParallelCompositeUploadException.of(cause, fCreatedObjects);
   }
 
   @NonNull
-  private static ApiFuture<ImmutableList<BlobId>> getPendingAndSuccessfulBlobIds(
+  private static ApiFuture<List<BlobId>> getPendingAndSuccessfulBlobIds(
       Executor exec, List<ApiFuture<BlobInfo>> pendingParts, List<BlobId> successfulParts) {
     ApiFuture<List<BlobInfo>> successfulList = ApiFutures.successfulAsList(pendingParts);
     // suppress any failure that might happen when waiting for any pending futures to resolve
     ApiFuture<List<BlobInfo>> catching =
         ApiFutures.catching(successfulList, Throwable.class, t2 -> ImmutableList.of(), exec);
 
-    ApiFuture<ImmutableList<BlobId>> fCreatedObjects =
+    ApiFuture<List<BlobId>> fCreatedObjects =
         ApiFutures.transform(
             catching,
             l ->