The following deployment structure cannot be validated against the XML schema:

<jboss-deployment-structure  xmlns="urn:jboss:deployment-structure:1.2">

    <deployment>
        <dependencies>
            <module name="foo"/>
        </dependencies>
    </deployment>

</jboss-deployment-structure>

This looks like a glitch in the schema where the module-alias element in deploymentType is missing a minOccurs="0".

The same holds for the filter element of resource-root, which should be optional according to the schema documentation.