Wicket warning about "id" attribute

When having installed the Projects feature, there's a Wicket warning about using component.setMarkupId() on login.

It comes from CmsSubAppIFrameCommunicationBehavior#bind

tag.put("id", CmsSubAppIFrameCommunicationBehavior.this.iFrameElementId);

Then org.apache.wicket.markup.ComponentTag#checkIdAttribute warns about the "id" attribute:

log.warn("Please use component.setMarkupId(String) to change the tag's 'id' attribute.");

Setting log level to INFO produces this just before the warning:

INFO  [CmsSubAppIFrameCommunicationBehavior.createScript:102] Add {key:iFrameElementId,value:projects-iframe as parameter to script