code: public ExpressionFactory getExpressionFactory()
      {
          Application application = getMyfacesApplicationInstance();
          if (application != null)
          {
              return application.getExpressionFactory();
          }
          throw new UnsupportedOperationException();
      }
docs: <p>
  Return the <code>ExpressionFactory</code> instance for this application. This instance is used by the convenience
  method <code>{@link #evaluateExpressionGet(javax.faces.context.FacesContext, java.lang.String, java.lang.Class)}.
  </code>
  </p>
  
  <p>
  The implementation must return the <code>ExpressionFactory</code> from the JSP container by calling <code>
  JspFactory.getDefaultFactory().getJspApplicationContext(servletContext).getExpressionFactory()</code>.
  </p>
  
  <p>
  An implementation is provided that throws <code>UnsupportedOperationException</code> so that users that decorate
  the <code>Application</code> continue to work.
  </p>
  
  @since 1.2
  @return