GraphSession.cloneImmediate(...) has a parameter that specifies whether any existing nodes should be removed (from the connector), and if this connector request succeeds and did remove those nodes, the method continues by attempting to purge these nodes from the cache. However, the request collects in a Set the Location for each of the removed nodes, so the order of these nodes cannot be guaranteed. And in fact when the cloneImmediate method walks them, the test was purging a parent node followed by a child node. Since purging the parent also purged all children (and other descendants), attempting to purge the child results in an exception.