docs: private synchronized void initialize()
      {
          if (!_initialized)
          {
              FacesContext context = FacesContext.getCurrentInstance();
  
              if (isFacelets2Enabled(context))
              {
                  logWarningIfLegacyFaceletViewHandlerIsPresent(context);
  
                  if (MyfacesConfig.getCurrentInstance(
                          context.getExternalContext()).isSupportJSPAndFacesEL())
                  {
                      _supportedLanguages = new ViewDeclarationLanguageStrategy[2];
                      _supportedLanguages[0] = new FaceletViewDeclarationLanguageStrategy();
                      _supportedLanguages[1] = new JspViewDeclarationLanguageStrategy();
                  }
                  else
                  {
                      _supportedLanguages = new ViewDeclarationLanguageStrategy[1];
                      _supportedLanguages[0] = new FaceletViewDeclarationLanguageStrategy();
                  }
              }
              else
              {
                  // Support JSP only
                  _supportedLanguages = new ViewDeclarationLanguageStrategy[1];
                  _supportedLanguages[0] = new JspViewDeclarationLanguageStrategy();
              }
  
              _initialized = true;
          }
      }