code: public Object processInvocation(final InterceptorContext context) throws Exception {
          final SecurityIdentity identity = context.getPrivateData(SecurityIdentity.class);
          if (identity != null) try {
              return identity.runAs(context);
          } catch (PrivilegedActionException e) {
              throw e.getException();
          } else {
              return context.proceed();
          }
      }
docs: {@inheritDoc}