public Map<String, Object> getRealmPrincipals(String name) {
        if (this.realmPrincipals == null) {
            return null;
        }
        Map<String, Object> principals = this.realmPrincipals.get(name);
        if (principals == null) {
            return null;
        }
        return Collections.unmodifiableMap(principals);
    }
Default implementation of the {@link PrincipalMap} interface.
<p>
*EXPERIMENTAL for Shiro 1.2 - DO NOT USE YET*

@since 1.2
core/src/main/java/org/apache/shiro/subject/SimplePrincipalMap.java