@Override
        protected byte[] getRememberedSerializedIdentity(SubjectContext subjectContext) {
            return new byte[0];
        }
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