mvn clean install -Dtycho.localArtifacts=ignore
instead. Note, however, that you then must use this build command for every build with that specific version number until you clear the build artifact (or the p2-local-metadata.properties) from your local repository. Otherwise, you might run into issues caused by the build using an outdated build artifact created by a previous build instead of re-building the plugin. More information on this issue is given in this thread and this bug tracker entry.You can find the built plugin in eclipse_plugin/target/google-java-format-eclipse-plugin-<version>.jar
With the current build setup, the Eclipse plugin build pulls the needed build artifacts of the google java format core from the maven repository and copies it into the eclipse_plugin/lib/
directory.
If you instead want to build against a local (snapshot) build of the core which is not available in a maven repository (local or otherwise), you will have to place the appropriate version into the eclipse_plugin/lib/
directory yourself before the build.