square/retrofit — pull request #470 by ypresto (2014-05-01 17:25:49+00:00)
Title: Add @PartMap annotation.

`@Query` and `@Field` have `@QueryMap` and `@FieldMap` to use with
Map for multiple parameters.
But there is no `@Part` alternative for Map.

We want to upload file with many metadata values,
so it would be better to have `@PartMap` annotation like other parameter
annotations.

Thanks for the great library!