Mark attribute 'outbound-socket-binding' in a reverse-proxy handler as 'required'

/subsystem=undertow/configuration=handler/reverse-proxy=my-rev-proxy/host=some-host:add()
{
    "outcome" => "failed",
    "failure-description" => {
        "WFLYCTL0412: Required services that are not installed:" => ["org.wildfly.network.outbound-socket-binding.undefined"],
        "WFLYCTL0180: Services with missing/unavailable dependencies" => ["org.wildfly.undertow.reverse-proxy.host.my-rev-proxy.some-host is missing [org.wildfly.network.outbound-socket-binding.undefined]"]
    },
    "rolled-back" => true
}