code: @Override
      public void run() {
          JCASecurityContext ctx = bootstrapContext.getJCASecurityContext();
          if (ctx != null)
              ctx.runInInboundSecurityContext(work);
          else
              work.run();
      }
docs: When this is invoked, the work is running with context on the thread.
  
  @see java.lang.Runnable.run()