Step 1 - find workspace location (optional)If you don"t know where is your workspace located follow these steps:right click on the project;Click on ResourceGo to your Location
My case: D:RepositoriesBitbucketcarolannpeacock.comJerseyHelloWorld
Step 3 - Edit org.eclipse.wst.common.project.facet.core.xml fileEdit .settingsorg.eclipse.wst.common.project.facet.core.xml and change the jst.web property to 3.1.
Step 4 - Refresh and CleanRight-click on the project and refresh followed by Project -> Cskinny ... to recompile the project.
Step 5 - Check the project facetsGoing back to project properties now it should be 3.1.
These steps will work for any dynamic web module version.