Duplicate results if endpoints respond with both the HITS and KWIC DataView

[Querela]

The upgrade of the fcs-sru-cqi-bridge changed the respond Data Views from the legacy KWIC format to the newer HITS format. To remain compatible with possible other SRU/FCS end users, the XMLStreamWriterHelper.writeResourceWithHitsDataViewLegacy method from the eu.clarin.sru.server.fcs package is used that effectively serializes hits in both Data View formats. It is marked as @Deprecated but was used to remain compatible.
Since the FCS-libraries and the Aggregator also want to remain compatible with older legacy endpoints they parses both formats and therefore shows each result twice. The DataViewParserKWIC automatically upgrades the legacy KWIC DataView into a HITS DataView so results can not be distinguished at the end of the process.

• Solution 1: dopping legacy support, ref
• Solution 2: changing DataViewParserKWIC (docs) to return the Legacy KWIC DataView.
  • Problem: All clients that rely on KWIC being auto-upgraded to HITS will suddenly miss results.
  • Solution: subclass LegacyDataViewKWIC from DataViewHits to keep the information but handle the change without noticable difference. Clients can optionally filter out legacy Data Views. Another way would be a new property to inform about the original media-type or whether it was upgraded.
    → For the aggregator this would be here