<version>1.0.0+</version>
          <association xml.itemsStyle="flat">
            <type>CoreExtension</type>
            <multiplicity>*</multiplicity>
          </association>
        </field>
      </fields>
    </class>
    <class xml.tagName="extension">
      <name>CoreExtension</name>
      <description>Describes a build extension to utilise.</description>
      <version>1.0.0+</version>