Check if ROS2 Parameters Exist with RCLCPP

In ROS1 there was the hasParam method. In ROS2, [there doesn't seem to be a way to check if a parameter exists](http://docs.ros2.org/bouncy/api/rclcpp/classrclcpp_1_1_node.html#a179590a0d3b2416636a1210995431c05) directly without attempting to get the value of the parameter. A) Is there a way to check if a parameter exists that I'm missing B) If not, why not?