code: protected MultiList<String> params(List<FormItem> formItems) {
          MultiList<String> params = new MultiList<>();
          for (FormItem formItem : formItems) {
              if(!formItem.isFile() && !params.contains(formItem.getFieldName())){
                  params.put(formItem.getFieldName(), formItem.getStreamAsString());
              }
          }
          return params;
      }
docs: Convenience method to get parameters in case <code>multipart/form-data</code> request was used.
  
  Returns a {@link MultiList} where keys are names of all parameters.
  
  @param formItems form items retrieved from <code>multipart/form-data</code> request.
  @return a {@link MultiList} where keys are names of all parameters.