Hi Wil and Johnny,
What Johnny says is I feel the right guidance to take, Wil.
Within a Bounded Context, your Messages/the API should be sharable with any component contained in it.
Thus, Commands, Events, Queries, and their possible responses should be freely sharable.
Between Bounded Contexts however, you share consciously.
Thus only the messages which are regarding to be common place between your Contexts.
So like I already pointed out, Johnny puts you on the right track.
However you decide to share the common language is up to you though.
Having a separate repository/jar/package/schema is all fine in my book, as long as you have separated the language within a Bounded Context from the language between Bounded Contexts.
Hope this helps.