Unwanted warnings when using shared license override file

[tpage-alfresco]

We are using a centralised license override file for all of our Java projects which means that every build contains a large number of log lines like:
[WARNING] dependency [org.antlr--antlr4-runtime--4.8-1] does not exist in project.
For some of our builds this is causing several thousand lines of warnings, which is pushing the build log dangerously close to the Travis limit.

This issue is very similar to #201 and a fix has previously been attempted in #300.