RESTMapping method can now rely on RESTMappings by passing versions parameter and taking the first match found by RESTMappings method. In addition
a UT that test the new method has been added.
The only change in logic to what was before is when calling RESTMapping
we search all defaultGroupVersion as opposed to just one when no mapping was found for provided versions.
With the introduction of batch/v1 and batch/v2alpha1, any
MultiRESTMapper that has per groupversion mappers (as a naive discovery
client would create) would end up being unable to call RESTMapping() on
batch.Jobs. As we finish up discovery we will need to be able to choose
prioritized RESTMappings based on the service discovery doc.
This change implements RESTMappings(groupversion) which returns all
possible RESTMappings for that kind. That allows a higher level call to
prioritize the returned mappings by server or client preferred version.
