https://bugzilla.redhat.com/show_bug.cgi?id=1667654
--- Comment #1 from Mat Booth mat.booth@redhat.com --- It looks like you are trying to use PDT from the upstream update site instead of the RPM from the Fedora repositories.
Please try clearing your externally installs plugins and installing from the Fedora repositories and seeing if that works for you:
$ mv ~/.eclipse ~/.eclipse-old $ sudo dnf install eclipse-pdt