@Override
    public void validate(Context context) {
        List<SearchCluster> clusters = context.model().getSearchClusters();
        for (SearchCluster cluster : clusters) {
            for (SchemaInfo spec : cluster.schemas().values()) {
                SDDocumentType docType = spec.fullSchema().getDocument();
                if (docType != null && spec.getIndexMode() == SchemaInfo.IndexMode.INDEX) {
                    validateDocument(context, cluster, spec.fullSchema(), docType);
                }
            }
        }
    }
This Validator iterates through all search cluster in the given VespaModel to make sure that there are no custom
structs defined in any of its search definitions.

@author Simon Thoresen Hult
config-model/src/main/java/com/yahoo/vespa/model/application/validation/SearchDataTypeValidator.java