/subsystem=xts:read-resource-description
...
        "attributes" => {
            "async-registration" => {
                "type" => BOOLEAN,
                "description" => "Initialize endpoints for asynchronous registration needed for WS-AT .NET integration.",
                "expressions-allowed" => true,
                "required" => false,
                "nillable" => true,
                "default" => false,
                "access-type" => "read-write",
                "storage" => "configuration",
                "restart-required" => "all-services"
            },

12:17:26,482 ERROR [org.jboss.as.controller] (Controller Boot Thread) 

OPVDX001: Validation error in standalone-xts.xml -------------------------------
|
|  670:         <xts-environment url="http://${jboss.bind.address:127.0.0.1}:8080/ws-c11/ActivationService"/>
|  671:         <default-context-propagation enabled="true"/>
|  672:         <async-registration enabled="${env.var:false}"/>
|                                   ^^^^ '${env.var:false}' isn't a valid value for the 'enabled' attribute
|
|  673:     </subsystem>
|  674: </profile>
|  675: <interfaces>
|
| The primary underlying error message was:
| > ParseError at [row,col]:[672,13]
| > Message: WFLYCTL0106: Invalid value '${env.var:false}' for attribute
| >   'enabled'
|
|-------------------------------------------------------------------------------

12:17:26,483 ERROR [org.jboss.as.server] (Controller Boot Thread) WFLYSRV0055: Caught exception during boot: org.jboss.as.controller.persistence.ConfigurationPersistenceException: WFLYCTL0085: Failed to parse configuration
	at org.jboss.as.controller.persistence.XmlConfigurationPersister.load(XmlConfigurationPersister.java:143)
	at org.jboss.as.server.ServerService.boot(ServerService.java:395)
	at org.jboss.as.controller.AbstractControllerService$1.run(AbstractControllerService.java:416)
	at java.lang.Thread.run(Thread.java:748)

12:17:26,484 FATAL [org.jboss.as.server] (Controller Boot Thread) WFLYSRV0056: Server boot has failed in an unrecoverable manner; exiting. See previous messages for details.

"result" => {
        "description" => "The configuration of the XST subsystem.",
        "deprecated" => {
            "since" => "3.0.0",
            "reason" => "Deprecated since the XTS feature set is rarely used and is considered legacy within development approaches nowadays."
        },