Make accept header check in validation case insensitive #37713

Job	Run time
CI Sanity Check	32s
Attach pull request number	3s
Initial JDK 17 Build	11m 30s
Calculate Test Jobs	16s
JVM Tests - JDK 17	35m 55s
JVM Tests - JDK 21	33m 33s
Quickstarts Compilation - JDK 17	5m 57s
JVM Tests - JDK 17 Windows	54m 30s
Gradle Tests - JDK 17	25m 40s
Maven Tests - JDK ${{ matrix.java.name }}	0s
Gradle Tests - JDK 17 Windows	50m 41s
Devtools Tests - JDK ${{ matrix.java.name }}	0s
Kubernetes Tests - JDK ${{ matrix.java.name }}	0s
Native Tests - Main	8m 14s
Native Tests - Data4	5m 3s
MicroProfile TCKs Tests	5m 49s
Native Tests - Virtual Thread - ${{ matrix.category }}	0s
Native Tests - Misc1	7m 21s
Native Tests - Misc2	5m 9s
Native Tests - Misc3	15m 2s
Native Tests - Misc4	17m 7s
Native Tests - Spring	8m 3s
Build report	43s
	4h 51m 8s

Provide feedback