The locationtech repository has changed URL:
(same for "releases" or "thirdparty" instead of "snapshots" at the end). It is documented here: https://bugs.eclipse.org/bugs/show_bug.cgi?id=528040
Similarly, the repository "boundlessgeo" has changed URL:
(documented here: https://www.osgeo.org/foundation-news/new-osgeo-repo/ )
Right now this prevents compiling the project.
All repositories are listed in the parent pom.xml at the root of the project, so this should be easy to fix. If I have the time, I might push a pull request for that soon.