Alright, so today I was playing with the out of the box af:table QBE feature, and I noticed that the inputText filters displayed at the top of the table header were case sensitive. I was intrigued and started to debug some internal classes only to be snapped by my fellow colleagues from the ADF Faces team that this is actually a built-in feature of the af:column tag:
This is correctly documented in the af:column tag documentation.
So, lesson learned: read the fraking doc before annoying your developer friends! >_<