code: public B allowRequestMethods(HttpMethod... methods) {
          requireNonNull(methods, "methods");
          checkArgument(methods.length > 0, "methods should not be empty.");
          for (int i = 0; i < methods.length; i++) {
              if (methods[i] == null) {
                  throw new NullPointerException("methods[" + i + ']');
              }
          }
          Collections.addAll(allowedRequestMethods, methods);
          return self();
      }
docs: Specifies the allowed set of HTTP request methods that should be returned in the
  CORS {@code "Access-Control-Allow-Methods"} response header.
  
  @param methods the {@link HttpMethod}s that should be allowed.
  @return {@code this} to support method chaining.