private SchemaValidator createValidator(File schemaDir, String schemaFile) {
        try {
            File file = new File(schemaDir + File.separator + "schema" + File.separator + schemaFile);
            return new SchemaValidator(file, new BaseDeployLogger());
        } catch (SAXException e) {
            throw new RuntimeException("Invalid schema '" + schemaFile + "'", e);
        } catch (IOException e) {
            throw new RuntimeException("IO error reading schema '" + schemaFile + "'", e);
        }
    }
Looks for schema files in config-model.jar and saves them in a temp dir. Uses schema files
in $VESPA_HOME/share/vespa/schema/[major-version].x/ otherwise

@return the directory the schema files are stored in
@throws IOException if it is not possible to read schema files
config-application-package/src/main/java/com/yahoo/config/model/application/provider/SchemaValidators.java