Autodetect object "hint" type for object queries faceting

[agazzarini]

At the moment, although the feature hasn't been merged in master, the object queries faceting assumes that for each query a requestor must specifiy also the "type" of facet he would expect.

Although it can be useful in some cases (e.g. disambiguation) usually it would be great if Solr would guess the requested type. How? I don't know at the moment