subject field in CSW is case sensitive

see

https://vanilla.geocat.net/geonetwork/srv/dut/csw?request=GetRecords&service=CSW&version=2.0.2&elementsetname=full&typenames=gmd%3AMD_Metadata&RESULTTYPE=results&constraintLanguage=CQL_TEXT&constraint_language_version=1.1.0&maxRecords=100&startPosition=1&constraint=%28%28Subject+LIKE+%27%25boundaries%25%27%29%29

vs

https://vanilla.geocat.net/geonetwork/srv/dut/csw?request=GetRecords&service=CSW&version=2.0.2&elementsetname=full&typenames=gmd%3AMD_Metadata&RESULTTYPE=results&constraintLanguage=CQL_TEXT&constraint_language_version=1.1.0&maxRecords=100&startPosition=1&constraint=%28%28Subject+LIKE+%27%25Boundaries%25%27%29%29

users don't expect this type of fields to be case sensitive

Start by reproducing the two CSW GetRecords URLs and trace how the Subject LIKE constraint is handled. Done means equivalent searches with different Subject casing return the same results, with regression coverage for the behavior.

Written by the indexing model from the issue text.