code: public String putJson(String endpoint, String params, JSONObject json) throws IOException {
          return this.putJson(endpoint, params, json, "");
      }
docs: Issues HTTP PUT request, returns response body as string.
  
  @param endpoint endpoint of request url
  @param params   request line parameters
  @param json     request body
  
  @return response body
  
  @throws IOException in case of any IO related issue