collisions in the namespace are silently ignored

[johnynek]

the class to jar graph is not a tree. So, some classes appear in multiple jars.

this code does not currently contemplate collisions like this. I think map semantics are simply overwriting collisions.

An example in our repo:

oboykin@Oscars-MacBook-Pro rankresearchv2 % jar tf bazel-rankresearchv2/external/jvm__org_glassfish_hk2_external__javax_inject/javax.inject.jar 
META-INF/
META-INF/MANIFEST.MF
javax/
javax/inject/
javax/inject/Inject.class
javax/inject/Qualifier.class
javax/inject/Singleton.class
javax/inject/Provider.class
javax/inject/Scope.class
javax/inject/Named.class

So this jar org.glassfish.hk2.external:javax-inject is just republishing some javax.inject classes: https://central.sonatype.com/artifact/org.glassfish.hk2.external/javax.inject

but you might also have those classes from another path, e.g. the standard javax.inject jar.