Feign changes capitalization of header-keys

[t-merten]

I run a wiremock-server which is configured to return a created-response with a location header. The location header is put with an uppercase "L". A simple springboot test checks if the response of the feign client is equal to a ResponseEntity.created(URI).
The test fails because the location-key in the header of the feign-response has changed to start with a lowercase "l" during the call Util#caseInsensitiveCopyOf in line 373:
result.put(key.toLowerCase(Locale.ROOT), new LinkedList<>());

In my opinion the method Util#caseInsensitiveCopyOf must not change the capitalization of header-keys.

I am using feign-core:13.1 with springboot 3.2.2

[youssef3wi]

The method is transformed into a case-sensitive copy caseSensitiveCopyOf.