{ "outcome" => "failed", "failure-description" => "WFLYJCA0114: Failed to load datasource class: com.mysql.cj.jdbc.MysqlXADataSource", "rolled-back" => true }

O erro acontece apos a execução da seguinte linha:

/subsystem=datasources/jdbc-driver=mysql:add(driver-name=mysql,driver-module-name=com.mysql,driver-xa-datasource-class-name=com.mysql.cj.jdbc.MysqlXADataSource)

console do eclipse apos o erro:

13:38:47,718 INFO [org.jboss.as.server] (Controller Boot Thread) WFLYSRV0212: Resuming server 13:38:47,721 ERROR [org.jboss.as] (Controller Boot Thread) WFLYSRV0026: WildFly Full 20.0.1.Final (WildFly Core 12.0.3.Final) started (with errors) in 6391ms - Started 423 of 656 services (5 services failed or missing dependencies, 388 services are lazy, passive or on-demand) 13:38:47,723 INFO [org.jboss.as] (Controller Boot Thread) WFLYSRV0060: Http management interface listening on http://127.0.0.1:9990/management 13:38:47,724 INFO [org.jboss.as] (Controller Boot Thread) WFLYSRV0051: Admin console listening on http://127.0.0.1:9990 13:39:45,092 ERROR [org.jboss.as.controller.management-operation] (management-handler-thread - 2) WFLYCTL0013: Operation ("add") failed - address: ([ ("subsystem" => "datasources"), ("jdbc-driver" => "mysql") ]) - failure description: "WFLYJCA0041: Failed to load module for driver [com.mysql]" 13:39:45,092 INFO [org.jboss.as.controller] (management-handler-thread - 2) WFLYCTL0183: Service status report WFLYCTL0186: Services which failed to start: service jboss.deployment.unit."agendamento-email-0.0.1-SNAPSHOT.war".INSTALL: WFLYSRV0153: Failed to process phase INSTALL of deployment "agendamento-email-0.0.1-SNAPSHOT.war"

modulo.xml:

<?xml version='1.0' encoding='UTF-8'?>

<module xmlns="urn:jboss:module:1.1" name="com.mysql">

    <resources>
        <resource-root path="conector"/>
    </resources>

    <dependencies>
        <module name="javax.api"/>
        <module name="javax.transaction.api"/>
    </dependencies>

    <module name="javax.transaction.api"/>
</module>

aqui esta o standalone.xml:

https://gist.github.com/GabrielRomanoo/a2160ffd15ecee92f12e31874d017e3f

Provavelmente você está tentando acessar o MySQL 8;

Na versão 8.x do MySql, o nome da classe que implementa java.sql.Driver no MySQL Connector / J foi alterado de com.mysql.jdbc.Driver para com.mysql.cj.jdbc.Driver . O nome da classe antiga foi descontinuado.

O wildfly também tem algumas configurações diferentes do JBoss 7.1 mostrado no curso.

Para configurar o driver do MySQL 8 no standalone.xml:

<driver name="mysql" module="com.mysql">
    <driver-class>com.mysql.cj.jdbc.Driver</driver-class>
    <xa-datasource-class>com.mysql.cj.jdbc.MysqlXADataSource</xa-datasource-class>
</driver>

Após isso, mude a tag driver no datasource para mysql. Adicionando o módulo no module.xml:

<module name="javax.transaction.api"/>

Dessa forma, deu certo para o driver mysql-connector-java-8.0.16-bin usando wildfly.

Outra opção é você instalar o MySQL 5 na sua máquina ao invés de tentar conectar o projeto no Mysql 8