code: static Map<Method, Method> toFallbackMethod(Map<Method, MethodHandler> dispatch) {
      Map<Method, Method> result = new LinkedHashMap<Method, Method>();
      for (Method method : dispatch.keySet()) {
        method.setAccessible(true);
        result.put(method, method);
      }
      return result;
    }
docs: If the method param of InvocationHandler.invoke is not accessible, i.e in a package-private
  interface, the fallback call in hystrix command will fail cause of access restrictions. But
  methods in dispatch are copied methods. So setting access to dispatch method doesn't take
  effect to the method in InvocationHandler.invoke. Use map to store a copy of method to invoke
  the fallback to bypass this and reducing the count of reflection calls.
  
  @return cached methods map for fallback invoking