@Override
  public void write(Output output, String boundary, String key, Object object)
      throws EncodeException {
    val map = toMap(object);
    for (val entry : map.entrySet()) {
      val writer = findApplicableWriter(entry.getValue());
      if (writer == null) {
        continue;
      }

      writer.write(output, boundary, entry.getKey(), entry.getValue());
    }
  }
A custom user's POJO writer.

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