I added natures to the project manually (I modified .project file). ok - I see -
Right mouse click on project --> Configure --> Add JBoss Tools Knowledge Base support - add
org.jboss.tools.jst.web.kb.kbbuilder as a project builder.
Unfortunately, "Add JBoss Tools Knowledge Base support" to the project and then "Close" the project leads to exceptions...
I'll create separate issue for it.