Yes it's possible, but in this case we have several options:
- Having empty URL in report
- Taking it from one of the LicenseMetadata for which we use alias 
- Allow specifying both LicenceMetadata and String (for instance use Object and check types in runtime)

Now we can use the 'license' static factory method that allows the creation of LicenseMetadata with\without URL (like: license("Apache 2") or license("Apache 2", "some url").