While working on JDK-8170578, we found that in ubuntu16.10
3 attributes are repeated
IPPPrintService>> readIPPResponse pwg-raster-document-resolution-supported
IPPPrintService>> readIPPResponse pwg-raster-document-sheet-back
IPPPrintService>> readIPPResponse pwg-raster-document-type-supported

which causes readIPPResponse() to create new hashmap.

If anything we wouldd expect that you may want to tie a HashMap to each group tag.
In which case the first one would be operational attributes, not printer attributes.
And it isn't done like that anyway. It just creates a new one "on demand" when
it sees the key is already used. This happens in the middle of processing a particular group.
We need to examine this creation of new hashmap logic.