private static ContentCluster createCluster(String sdContent) {
        return new ContentClusterBuilder().build(
                ContentClusterUtils.createMockRoot(
                        List.of(new SchemaBuilder().content(sdContent).build())));
    }
Test fixture to setup current and next content clusters used for change validation.

@author geirst
config-model/src/test/java/com/yahoo/vespa/model/application/validation/change/search/ContentClusterFixture.java