Integer overflow in total count in grouping results

When doing a Grouping search in solr cloud you can get a negative number for the total found.

This is caused by the accumulated total being held in an integer and not a long.

 

example result:

{{{ "responseHeader": { "status": 0, "QTime": 9231, "params":

{ "q": "decade:200", "indent": "true", "fl": "decade", "wt": "json", "group.field": "decade", "group": "true", "_": "1542773674247" }

}, "grouped": { "decade": { "matches": -629516788, "groups": [ { "groupValue": "200", "doclist": { "numFound": -629516788, "start": 0, "maxScore": 1.9315376, "docs": [

{ "decade": "200" }

] } } ] } } }}}

 

result without grouping:
{{{ "responseHeader": { "status": 0, "QTime": 1063, "params":

{ "q": "decade:200", "indent": "true", "fl": "decade", "wt": "json", "_": "1542773791855" }

}, "response": { "numFound": 3665450508, "start": 0, "maxScore": 1.9315376, "docs": [

{ "decade": "200" }

,

{ "decade": "200" }

,

{ "decade": "200" }

,

{ "decade": "200" }

,

{ "decade": "200" }

,

{ "decade": "200" }

,

{ "decade": "200" }

,

{ "decade": "200" }

,

{ "decade": "200" }

,

{ "decade": "200" }

] } }}}