private Element generateContainerElementWithRenderer(String rendererId) {
        return DomBuilderTest.parse(
                "<container id='default' version='1.0'>",
                "  <search>",
                String.format("    <renderer id='%s'/>", rendererId),
                "  </search>",
                "</container>");
    }
Tests for "core functionality" of the container model, e.g. ports, or the 'components' and 'bundles' configs.

Before adding a new test to this class, check if the test fits into one of the other existing subclasses
of {@link ContainerModelBuilderTestBase}. If not, consider creating a new subclass.

@author gjoranv
config-model/src/test/java/com/yahoo/vespa/model/container/xml/ContainerModelBuilderTest.java