code: public Operation setMetadata(Map<String, String> metadata, OperationOption... options) {
      return setMetadata(getMetadata().toBuilder().setValues(metadata).build(), options);
    }
docs: Sets the metadata for this instance, fingerprint value is taken from this instance's {@code
  tags().fingerprint()}.
  
  @return a zone operation if the set request was issued correctly, {@code null} if the instance
  was not found
  @throws ComputeException upon failure