Resolve licensing issue from #151 #539
Description
PR #151 added https://github.com/prometheus/client_java/blob/11408239035f02a125fe3c860f05fcd0be1e7873/simpleclient_spring_boot/src/test/java/io/prometheus/client/matchers/CustomMatchers.java which contains code under a copyleft license, which is not thus compatible with the Apache 2.0 license this repo uses.
One option would be to rewriting this code ourselves. Given that this is all for Spring v1 which has been superseded by v2 and this code hasn't changed in a good while we could also remove the test, or the entire module.