protected FactoryBuilderSupport getProxyBuilder() {
        FactoryBuilderSupport proxy = localProxyBuilder.get();
        if (proxy == null) {
            return globalProxyBuilder;
        } else {
            return proxy;
        }
    }
protected FactoryBuilderSupport getProxyBuilder ( ) { FactoryBuilderSupport proxy = localProxyBuilder . get ( ) ; if ( proxy == null ) { return globalProxyBuilder ; } else { return proxy ; } }
Proxy builders are useful for changing the building context, thus
enabling mix &amp; match builders.

@return the current builder that serves as a proxy.<br>