apollo-common/src/main/java/com/ctrip/framework/apollo/common/controller/GlobalDefaultExceptionHandler.java/GlobalDefaultExceptionHandler/badRequest
class GlobalDefaultExceptionHandler:  @ExceptionHandler({HttpRequestMethodNotSupportedException.class, HttpMediaTypeException.class})
  public ResponseEntity<Map<String, Object>> badRequest(HttpServletRequest request,
                                                        ServletException ex) {
    return handleError(request, BAD_REQUEST, ex, WARN);
  }