In our application we used the constants from following myfaces Interface: https://svn.apache.org/repos/asf/myfaces/site/publish/myfaces-commons/apidocs/index.html?org/apache/myfaces/renderkit/html/package-summary.html
Getting rid of myfaces, is there a substitute in jsf 2.3?
No, there is no alternative for it - but you can just use plain string or create your own constants. Mojarra may have similar constants but just dont use MyFaces or Mojarra internal classes.