code: public RequestBody buildRequestBodyFormEncoding(Map<String, Object> formParams) {
          FormEncodingBuilder formBuilder  = new FormEncodingBuilder();
          for (Entry<String, Object> param : formParams.entrySet()) {
              formBuilder.add(param.getKey(), parameterToString(param.getValue()));
          }
          return formBuilder.build();
      }
docs: Build a form-encoding request body with the given form parameters.
  
  @param formParams Form parameters in the form of Map
  @return RequestBody