private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.translate.v3.GcsDestination,
            com.google.cloud.translate.v3.GcsDestination.Builder,
            com.google.cloud.translate.v3.GcsDestinationOrBuilder>
        getGcsDestinationFieldBuilder() {
      if (gcsDestinationBuilder_ == null) {
        if (!(destinationCase_ == 1)) {
          destination_ = com.google.cloud.translate.v3.GcsDestination.getDefaultInstance();
        }
        gcsDestinationBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.translate.v3.GcsDestination,
                com.google.cloud.translate.v3.GcsDestination.Builder,
                com.google.cloud.translate.v3.GcsDestinationOrBuilder>(
                (com.google.cloud.translate.v3.GcsDestination) destination_,
                getParentForChildren(),
                isClean());
        destination_ = null;
      }
      destinationCase_ = 1;
      onChanged();
      return gcsDestinationBuilder_;
    }
<pre>
Optional. Google Cloud Storage destination for the translation output,
e.g., `gs://my_bucket/my_directory/`.

The destination directory provided does not have to be empty, but the
bucket must exist. If a file with the same name as the output file
already exists in the destination an error will be returned.

For a DocumentInputConfig.contents provided document, the output file
will have the name "output_[trg]_translations.[ext]", where
- [trg] corresponds to the translated file's language code,
- [ext] corresponds to the translated file's extension according to its
mime type.


For a DocumentInputConfig.gcs_uri provided document, the output file will
have a name according to its URI. For example: an input file with URI:
`gs://a/b/c.[extension]` stored in a gcs_destination bucket with name
"my_bucket" will have an output URI:
`gs://my_bucket/a_b_c_[trg]_translations.[ext]`, where
- [trg] corresponds to the translated file's language code,
- [ext] corresponds to the translated file's extension according to its
mime type.


If the document was directly provided through the request, then the
output document will have the format:
`gs://my_bucket/translated_document_[trg]_translations.[ext]`, where
- [trg] corresponds to the translated file's language code,
- [ext] corresponds to the translated file's extension according to its
mime type.

If a glossary was provided, then the output URI for the glossary
translation will be equal to the default output URI but have
`glossary_translations` instead of `translations`. For the previous
example, its glossary URI would be:
`gs://my_bucket/a_b_c_[trg]_glossary_translations.[ext]`.

Thus the max number of output files will be 2 (Translated document,
Glossary translated document).

Callers should expect no partial outputs. If there is any error during
document translation, no output will be stored in the Cloud Storage
bucket.
</pre>

<code>
.google.cloud.translation.v3.GcsDestination gcs_destination = 1 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-translate/proto-google-cloud-translate-v3/src/main/java/com/google/cloud/translate/v3/DocumentOutputConfig.java