docs: public void marshall(AttachToIndexRequest attachToIndexRequest, ProtocolMarshaller protocolMarshaller) {
  
          if (attachToIndexRequest == null) {
              throw new SdkClientException("Invalid argument passed to marshall(...)");
          }
  
          try {
              protocolMarshaller.marshall(attachToIndexRequest.getDirectoryArn(), DIRECTORYARN_BINDING);
              protocolMarshaller.marshall(attachToIndexRequest.getIndexReference(), INDEXREFERENCE_BINDING);
              protocolMarshaller.marshall(attachToIndexRequest.getTargetReference(), TARGETREFERENCE_BINDING);
          } catch (Exception e) {
              throw new SdkClientException("Unable to marshall request to JSON: " + e.getMessage(), e);
          }
      }