any way to post json document to a MoreLikeThisHandler?

[Matt Work Coarr]

Hello,

Using a MoreLikeThisHandler, I was hoping to be able to pass in in the post
body a json document (the same format as a document indexed in my core, but
the document in the request is not and should not be added to the core).

I'm thinking it would handle an incoming document similar to how the
/update handler can split up a json document into the set of fields defined
in the schema (or auto created fields).

For instance, my input document would look like this:

{
  "id": 1234,
  "field1": "blah blah blah",
  "field2": "foo bar",
  "field3": 112233
}

And then I want to be able to use the MoreLikeThis query parameters to
determine which fields are used in the MLT comparison.

Thanks,
Matt