null pointer exception when invoking "close" on a registration of a RPC implementation

I have a MD SAL service implementation the registers during an "onSessionInitiated" method. During the "stopImpl" method the registration is closed and a NullPointerException is thrown.

The issue seems to be that during the close the delegate for the service is set to "null" and this causes the exception in RuntimeCodeHelper as it attempts to retrieve the class of the parameter before checking if it is null.