code: public FilterFunction dynamic(final String name,
                                    final Optional<String> meta)
      {
          return dynamic(name,
                         meta,
                         Optional.empty());
      }
docs: An arbitrary constraint that uses {@link be.objectify.deadbolt.java.DynamicResourceHandler#isAllowed(String, Optional, DeadboltHandler, Http.RequestHeader)}
  to determine access.
  
  @param name the name of the constraint
  @param meta additional information passed to {@link be.objectify.deadbolt.java.DynamicResourceHandler#isAllowed(String, Optional, DeadboltHandler, Http.RequestHeader)}
  @return a function that wraps the constraint
  @see ConstraintLogic#dynamic(Http.RequestHeader, DeadboltHandler, Optional, String, Optional, Function, TriFunction, ConstraintPoint)