A SessionContextGroup instance method for adding a handler for context change.
The callback to be invoked. Is invoked when (a) the context changes or (b) immediately after getting created if the context is already set.
Optional
contextType: stringThe context type this handler should listen to. If not specified, a global handler for all context types will get created. Only one global handler is allowed per SessionContextGroup.
The SessionContextGroup's id.
An instance of a SessionContextGroup