Rename Multiset collector parameter names to be consistent with other collector factories.
Rename Multiset collector parameter names to be consistent with other collector factories.

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xasx/guava,google/guava,mosoft521/guava,berndhopp/guava,mosoft521/guava,DavesMan/guava,typetools/guava,typetools/guava,DavesMan/guava,Xaerxess/guava,google/guava,EdwardLee03/guava,Xaerxess/guava,xasx/guava,mosoft521/guava,berndhopp/guava,rgoldberg/guava,EdwardLee03/guava,rgoldberg/guava,google/guava