Java examples crash when closing connections

All the Java examples now crash when the connection is closed. Background: our Java SWIG layer sets up callbacks for cursors/sessions/connections that are closed – needed so that the Java objects associated with these are tagged so that a Java reference on a closed handle will give an appropriate Java exception. The callback is now being called with a cursor on "WiredTigerLAS.wt" that the Java code did not explicitly open, and the WT_CURSOR.lang_private field is NULL, the SWIG layer does not handle this.