requiredResourceContent property
Resource path → text that at least one copy of it must contain.
For a resource several jars ship at the same path, read by a library
that looks at every copy (ClassLoader.getResources, as service
registries do): when the jars are merged into one, a copy silently
replaces the others, and the file being present says nothing about
whether the copy that was needed survived. This checks that it did.
It does not check which copy comes first. For a library that reads
only the first (getResource), make sure no other jar ships the path.
Implementation
final Map<String, String> requiredResourceContent;