I think this mapping is backwards.  The use case is that I want a bunch of things to fall under a specific name, so I really want:

"Apache v2" -> ["The Apache v2", "Version 2 of Apache", "Apache Software v2"]

The mapping is then:

LicenseMetadata -> List<LicenseMetadata>

But I also want to be able to specify just a "String" in the case where I have to specify a LicenseMetadata.