jpa/subsystem/src/main/java/org/jboss/as/jpa/processor/PersistenceProviderHandler.java
private static Set<ClassLoader> allDeploymentModuleClassLoaders(DeploymentUnit deploymentUnit) {
        Set<ClassLoader> deploymentClassLoaders = new HashSet<ClassLoader>();
        final DeploymentUnit topDeploymentUnit = DeploymentUtils.getTopDeploymentUnit(deploymentUnit);
        final Module toplevelModule = topDeploymentUnit.getAttachment(Attachments.MODULE);
        if (toplevelModule != null) {
            deploymentClassLoaders.add(toplevelModule.getClassLoader());
            final List<DeploymentUnit> subDeployments = topDeploymentUnit.getAttachmentList(Attachments.SUB_DEPLOYMENTS);
            for (DeploymentUnit subDeploymentUnit: subDeployments) {
                final Module subDeploymentModule = subDeploymentUnit.getAttachment(Attachments.MODULE);
                if (subDeploymentModule != null) {
                    deploymentClassLoaders.add(subDeploymentModule.getClassLoader());
                }
            }
        }
        return deploymentClassLoaders;
    }
private static Set<ClassLoader> allDeploymentModuleClassLoaders(DeploymentUnit deploymentUnit) {
        Set<ClassLoader> deploymentClassLoaders = new HashSet<ClassLoader>();
        final DeploymentUnit topDeploymentUnit = DeploymentUtils.getTopDeploymentUnit(deploymentUnit);
        final Module toplevelModule = topDeploymentUnit.getAttachment(Attachments.MODULE);
        if (toplevelModule != null) {
            deploymentClassLoaders.add(toplevelModule.getClassLoader());
            final List<DeploymentUnit> subDeployments = topDeploymentUnit.getAttachmentList(Attachments.SUB_DEPLOYMENTS);
            for (DeploymentUnit subDeploymentUnit: subDeployments) {
                final Module subDeploymentModule = subDeploymentUnit.getAttachment(Attachments.MODULE);
                if (subDeploymentModule != null) {
                    deploymentClassLoaders.add(subDeploymentModule.getClassLoader());
                }
            }
        }
        return deploymentClassLoaders;
    }
returns the toplevel deployment module classloader and all subdeployment classloaders

@param deploymentUnit
@return