build warnings: same class in multiple .jars

[vlukashov]

When running mvn jetty:run on a freshly cloned repo, I am getting the following warning in the build log:

[WARNING] com.google.common.util.concurrent.internal.InternalFutureFailureAccess scanned from multiple locations: jar:file:///Users/viktor/.m2/repository/com/google/guava/failureaccess/1.0/failureaccess-1.0.jar!/com/google/common/util/concurrent/internal/InternalFutureFailureAccess.class, jar:file:///Users/viktor/.m2/repository/com/google/guava/guava/27.0-jre/guava-27.0-jre.jar!/com/google/common/util/concurrent/internal/InternalFutureFailureAccess.class
[WARNING] com.google.common.util.concurrent.internal.InternalFutures scanned from multiple locations: jar:file:///Users/viktor/.m2/repository/com/google/guava/failureaccess/1.0/failureaccess-1.0.jar!/com/google/common/util/concurrent/internal/InternalFutures.class, jar:file:///Users/viktor/.m2/repository/com/google/guava/guava/27.0-jre/guava-27.0-jre.jar!/com/google/common/util/concurrent/internal/InternalFutures.class

I would not want to see any such warnings in an example project that I download from vaadin.com/start.

[anasmi]

Can't reproduce

[vlukashov]

This issue seems to only concern the V15 branch (ccdm) and does not appear in the V14.x branch (master). At the moment the HEAD of the ccdm branch is broken (as well as many other V15 master builds), but it can be reproduced e.g. with the previous V15 alpha: 2f8fe52