code: @Override
  	public RequestBody convert(T value) throws IOException {
  		Buffer buffer = new Buffer();
  
  		try {
  			binderContext.serialize(value, buffer.outputStream());
  			return RequestBody.create(MEDIA_TYPE, buffer.readByteString());
  		} catch (Exception e) {
  			e.printStackTrace();
  			return null;
  		} finally {
  			buffer.close();
  		}
  
  	}
docs: /* (non-Javadoc)
  @see retrofit2.Converter#convert(java.lang.Object)