Custom collectors for grouping

[Ravi Solr <ra...@gmail.com>]

All,

Business needs changes to the groping functionality (using  solr 5.4.)
The changes are passing passing couple of extra params for sorting ,
changes to collector for sorting mechanism(user species the field and the
3/4 values in which documents are sorted in the order of preference and
with other criteria), regrouping of the documents in response.

I am looking for guidance in wiring the new custom collector with the
default search request handler.  Also any suggestions for which collector
is recommended for changes?
Any other suggestions for making the code optimal for performance?


Thanks
Ravi