@Override
  protected void write(Output output, String key, Object value) throws EncodeException {
    val string =
        new StringBuilder()
            .append("Content-Disposition: form-data; name=\"")
            .append(key)
            .append('"')
            .append(CRLF)
            .append("Content-Type: text/plain; charset=")
            .append(output.getCharset().name())
            .append(CRLF)
            .append(CRLF)
            .append(value.toString())
            .toString();

    output.write(string);
  }
A writer for a single parameter.

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