private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.translate.v3.GcsInputSource,
            com.google.cloud.translate.v3.GcsInputSource.Builder,
            com.google.cloud.translate.v3.GcsInputSourceOrBuilder>
        getGcsInputSourceFieldBuilder() {
      if (gcsInputSourceBuilder_ == null) {
        if (!(sourceCase_ == 3)) {
          source_ = com.google.cloud.translate.v3.GcsInputSource.getDefaultInstance();
        }
        gcsInputSourceBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.translate.v3.GcsInputSource,
                com.google.cloud.translate.v3.GcsInputSource.Builder,
                com.google.cloud.translate.v3.GcsInputSourceOrBuilder>(
                (com.google.cloud.translate.v3.GcsInputSource) source_,
                getParentForChildren(),
                isClean());
        source_ = null;
      }
      sourceCase_ = 3;
      onChanged();
      return gcsInputSourceBuilder_;
    }
<pre>
Google Cloud Storage file source.
</pre>

<code>.google.cloud.translation.v3.GcsInputSource gcs_input_source = 3;</code>
java-translate/proto-google-cloud-translate-v3/src/main/java/com/google/cloud/translate/v3/ImportAdaptiveMtFileRequest.java