fix: MapTypeAdapterFactory rejects duplicate keys on write (mirror of #3006 read-side)#3036

andrewstellman wants to merge 2 commits into

google:maingoogle/gson:mainfrom

andrewstellman:qpb/bug-002-map-duplicate-keys-writeandrewstellman/gson:qpb/bug-002-map-duplicate-keys-writeCopy head branch name to clipboard