This fixes the Kokoro tests broken by []
Unfortunately this means that the return type changes from a Map to an Object as well,
so all of the .get() lines need to turn into []. Yay weakly typed languages. And
apparently in some error conditions this method could already return the Object type
anyway, even if you passed in a Map, so it's just poorly designed.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=213808477
ae2c1071f1