prevent NPE on closing already closed sessions
prevent NPE on closing already closed sessions

mosoft521/jodd,mtakaki/jodd,oblac/jodd,Artemish/jodd,southwolf/jodd,Artemish/jodd,wsldl123292/jodd,javachengwc/jodd,vilmospapp/jodd,oblac/jodd,javachengwc/jodd,mohanaraosv/jodd,wsldl123292/jodd,oetting/jodd,mtakaki/jodd,vilmospapp/jodd,javachengwc/jodd,mtakaki/jodd,vilmospapp/jodd,tempbottle/jodd,oetting/jodd,tempbottle/jodd,oetting/jodd,southwolf/jodd,oblac/jodd,wsldl123292/jodd,tempbottle/jodd,mohanaraosv/jodd,wjw465150/jodd,oblac/jodd,southwolf/jodd,wsldl123292/jodd,mosoft521/jodd,wjw465150/jodd,tempbottle/jodd,mosoft521/jodd,mtakaki/jodd,mohanaraosv/jodd,javachengwc/jodd,mohanaraosv/jodd,Artemish/jodd,mosoft521/jodd,oetting/jodd,Artemish/jodd,wjw465150/jodd,Artemish/jodd,wjw465150/jodd,vilmospapp/jodd,vilmospapp/jodd,southwolf/jodd