If a non-CDI deployment (contains no beans.xml nor a bean with a bean defining annotation nor a session bean) attempts to access the CDI container using CDI.current() before TCCLSingletonService is started (and org.jboss.weld.bootstrap.api.SingletonProvider initialized with ModuleGroupSingletonProvider) then SingletonProvider is incorrectly initialized with the default impl (RegistrySingletonProvider). As a result,
subsequent CDI deployments fail with java.lang.RuntimeException: SingletonProvider is already initialized....