As a maven user, I want headers I defined to be passed with every request. However, HTTP headers defined in the settings.xml are not always passed. Depending on what is being requested, maven seems to use different http libraries that don't behave the same. I can see this by looking at our web access logs:
"GET /nexus/<redacted>/0.1-SNAPSHOT/maven-metadata.xml HTTP/1.1" 200 - "Apache-Maven/3.3.3 (Java 1.8.0_45; Linux 2.6.32-504.12.2.el6.x86_64)"
"GET /nexus/content/repositories/snapshots/<redacted>/0.10-SNAPSHOT/<redacted>0.10-20150619.165444-1.war.sha1 HTTP/1.1" 200 MyHTTPHeader "Apache-HttpClient/4.3.5 (java 1.5)"