Http query string to upperlower case


I’m using a url to wich my customer send datas as HTTP GET parameters :

This sends to my pipeline 3 string variables with their value:
param1 = value1
PaRaM2 = VaLue2
pArAm3 = vAlUE3

My problem is that my customer cannot garanty the letter case used for the params name on each sending, hence this is not a reliable entry.

My question :
How to force the case for each variable ? For example to have :
PARAM1 = value1
PARAM2 = VaLue2
hence allowing me to use them in mappings,

Thanks !