@Override
  public void write(Output output, String boundary, String key, Object value)
      throws EncodeException {
    output.write("--").write(boundary).write(CRLF);
    write(output, key, value);
    output.write(CRLF);
  }
A base writer class.

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