docs: public RequestBuilder createFileUploadRequestBuilder(String httpUrl, String methodName, String reqBodyAsString) throws IOException {
          Map<String, Object> fileFieldNameValueMap = getFileFieldNameValue(reqBodyAsString);
  
          List<String> fileFieldsList = (List<String>) fileFieldNameValueMap.get(FILES_FIELD);
  
          MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create();
  
          /*
  	 * Allow fileFieldsList to be null.
  	 * fileFieldsList can be null if multipart/form-data is sent without any files
  	 * Refer Issue #168 - Raised and fixed by santhoshTpixler
  	 */
          if(fileFieldsList != null) {
          	buildAllFilesToUpload(fileFieldsList, multipartEntityBuilder);
  	}
  
          buildOtherRequestParams(fileFieldNameValueMap, multipartEntityBuilder);
  
          buildMultiPartBoundary(fileFieldNameValueMap, multipartEntityBuilder);
  
          return createUploadRequestBuilder(httpUrl, methodName, multipartEntityBuilder);
      }