The following probably does not matter much because I am not an OpenJDK
contributor, but personally
I think throwing an UnsupportedOperationException is reasonable:
1. It is consistent with the other methods which also only work for one
specific variant
2. Code which calls UUID.version() on a non-variant 2 UUID is obviously
already functionally broken;
I don't think maintaining backward compatibility here adds any value
Regarding the pull request, I would recommend the following changes:
1. Replace ` ` with a normal space, that should work as well and is
easier to read
2. Add a sentence to the method description (and not only to the `@throws`
tag), that this method
is only meaningful for variant 2 UUIDs, see for example the documentation
for `timestamp()` for
how this sentence should look like to be consistent:
https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/util/UUID.html#timestamp()
Kind regards
