Messaging's HTTPUpgradeService is importing org.jboss.as.remoting.SimpleHttpUpgradeHandshake but then overrides its method. So just implement this directly and drop the org.jboss.as.remoting dependency.

To be fair, SimpleHttpUpgradeHandshake also includes a complex 'FlexBase64' inner class, but undertow-core provides the same class. HttpUpgradeHandshake itself is from undertow-core so there's no reason not to use the Undertow class. (The same is true in SimpleHttpUpgradeHandshake.)