@Override
        protected void forgetIdentity(Subject subject) {
        }
Tests the {@link AbstractRememberMeManager#getRememberedPrincipals(SubjectContext)} method
implementation when the internal
{@link AbstractRememberMeManager#getRememberedSerializedIdentity(SubjectContext)} method
returns null or empty bytes.
core/src/test/java/org/apache/shiro/mgt/AbstractRememberMeManagerTest.java