Solving "JPA Project Change Event Handler (waiting)" annoying message from Eclipse

I'm using Eclipse Oxygen IDE and I'm always getting this annoying message "JPA Project Change Event Handler (waiting)" after saving a file, but I'm not using JPA in my project.

I tried to turn off the JPA validators under Preferences, with no success and the message kept appearing. Now I've found out that the guilty for the message appearing is the Dali/JPT plugin.
Since I do not need this plugin, I uninstalled it from the "Preferences" > "Install/Update"> then click again in the "Uninstall or update" link under that tab and finally I've selected, from the "Installed Software", the "Dali Java Persistence Tools - JPA Support" entry. Then I uninstallled it.

Problem solved!