I can't find record of Picard's SamGroupPairs
My group is using a software pipeline that includes some tools that are several years old and I can't find documentation for, or even record of, one of them. The tool is SamGroupPairs, that's supposedly from Picard version 1.91. We have a local copy of the tool, but Google turned up no results for it and I couldn't find it in the GitHub repository (in neither the current version nor the commit in which version 1.91 was published).
My original purpose was to determine exactly what it's doing and to consider any more recent tools that would be better and/or still supported. Now, I'm just hoping to find any information on it at all.