public LdapContext getSystemLdapContext() throws NamingException {
        return getLdapContext(getSystemUsername(), getSystemPassword());
    }
This implementation delegates to {@link #getLdapContext(Object, Object)} using the
{@link #getSystemUsername() systemUsername} and {@link #getSystemPassword() systemPassword} properties as
arguments.

@return the system LdapContext
@throws NamingException if there is a problem connecting to the LDAP directory
core/src/main/java/org/apache/shiro/realm/ldap/JndiLdapContextFactory.java