private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.storagebatchoperations.v1.PutMetadata,
            com.google.cloud.storagebatchoperations.v1.PutMetadata.Builder,
            com.google.cloud.storagebatchoperations.v1.PutMetadataOrBuilder>
        getPutMetadataFieldBuilder() {
      if (putMetadataBuilder_ == null) {
        if (!(transformationCase_ == 8)) {
          transformation_ =
              com.google.cloud.storagebatchoperations.v1.PutMetadata.getDefaultInstance();
        }
        putMetadataBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.storagebatchoperations.v1.PutMetadata,
                com.google.cloud.storagebatchoperations.v1.PutMetadata.Builder,
                com.google.cloud.storagebatchoperations.v1.PutMetadataOrBuilder>(
                (com.google.cloud.storagebatchoperations.v1.PutMetadata) transformation_,
                getParentForChildren(),
                isClean());
        transformation_ = null;
      }
      transformationCase_ = 8;
      onChanged();
      return putMetadataBuilder_;
    }
<pre>
Updates object metadata. Allows updating fixed-key and custom metadata
and fixed-key metadata i.e. Cache-Control, Content-Disposition,
Content-Encoding, Content-Language, Content-Type, Custom-Time.
</pre>

<code>.google.cloud.storagebatchoperations.v1.PutMetadata put_metadata = 8;</code>
java-storagebatchoperations/proto-google-cloud-storagebatchoperations-v1/src/main/java/com/google/cloud/storagebatchoperations/v1/Job.java