In case you're using ops4j/pax.url, the configuration in settings.xml is slightly different from maven-resolver-transport-http:

<server>
    <id>my-server</id>
    <configuration>
        <httpHeaders>
            <httpHeader>
                <name>Authorization</name>
                <value>Bearer TOKEN</value>
            </httpHeader>
        </httpHeaders>
    </configuration>
</server>

source: https://github.com/ops4j/org.ops4j.pax.url