I am using a fresh install of STS 3.8.3 and I am unable to add the JPA facet to an EJB project:
If I try to create a JPA project, I cannot find that option:>
Go to Help -> Install New Software -> in the work with drop down , choose one with "https://download.eclipse.org/releases/*".
In the result you will be able to see Database Development. Choose the database you wish to configure.