/subsystem=elytron/authentication-context=auth-context:add()
/subsystem=elytron:write-attribute(name=default-authentication-context,value=auth-context)
{
    "outcome" => "success",
    "response-headers" => {
        "operation-requires-reload" => true,
        "process-state" => "reload-required"
    }
}

/subsystem=elytron:read-resource-description(recursive=false)
{
    ...
    "default-authentication-context" => {
        "type" => STRING,
        "description" => "The default authentication context to be associated with all deployments.",
        "expressions-allowed" => false,
        "required" => false,
        "nillable" => true,
        "capability-reference" => "org.wildfly.security.authentication-context",
        "min-length" => 1L,
        "max-length" => 2147483647L,
        "access-type" => "read-write",
        "storage" => "configuration",
        "restart-required" => "no-services"
    },   
    ...
}