public PermissionResolver getPermissionResolver() {
        return this.permissionResolver;
    }
Returns the PermissionResolver to be used on <em>all</em> configured realms, or <code>null</code> (the default)
if all realm instances will each configure their own permission resolver.

@return the PermissionResolver to be used on <em>all</em> configured realms, or <code>null</code> (the default)
if realm instances will each configure their own permission resolver.
@since 1.0
core/src/main/java/org/apache/shiro/authz/ModularRealmAuthorizer.java