code: public static void setFactory(String factoryName,
                                    String implName) {
  
          FactoryFinderInstance manager =
                FACTORIES_CACHE.getApplicationFactoryManager();
          manager.addFactory(factoryName, implName);
  
      }
docs: <p>This method will store the argument
  <code>factoryName/implName</code> mapping in such a way that
  {@link #getFactory} will find this mapping when searching for a
  match.</p>
  <p/>
  <p>This method has no effect if <code>getFactory()</code> has
  already been called looking for a factory for this
  <code>factoryName</code>.</p>
  <p/>
  <p>This method can be used by implementations to store a factory
  mapping while parsing the Faces configuration file</p>
  
  @throws IllegalArgumentException if <code>factoryName</code> does not
  identify a standard JavaServer Faces factory name
  @throws NullPointerException     if <code>factoryname</code>
  is null