Since NXP-22488, running mvn clean in nuxeo-web-ui repository deletes the bower_components directory.
As a Web UI Developer, you might:
~/workspace/nuxeo-web-ui/bower_components$ ln -s ~/workspace/nuxeo-ui-elements
in order to test local changes in nuxeo-ui-elements.
If you do run mvn clean install with such sym link, your nuxeo-ui-elements directory will be deleted along with any unpushed pending changes