@Override
  protected void write(Output output, String key, Object value) throws EncodeException {
    writeFileMetadata(output, key, null, null);

    byte[] bytes = (byte[]) value;
    output.write(bytes);
  }
A byte array writer.

@author Artem Labazin
form/src/main/java/feign/form/multipart/ByteArrayWriter.java