[standalone@localhost:9990 /] /subsystem=modcluster/proxy=default:write-attribute(name=ssl-context, value=applicationSSC)
{
    "outcome" => "failed",
    "failure-description" => "WFLYCTL0158: Operation handler failed: java.lang.IllegalArgumentException: WFLYCTL0484: Attribute definition of attribute 'ssl-context' is null",
    "rolled-back" => true
}