private void generateFunctionService() throws SAXException {
    Collection<Function> functions = Collections.emptyList();
    if (cache instanceof CacheCreation) {
      if (creation.hasFunctionService()) {
        functions = creation.getFunctionServiceCreation().getFunctionList();
      }
    } else {
      functions = FunctionService.getRegisteredFunctions().values();
    }
    if (!generateDefaults() && functions.isEmpty()) {
      return;
    }
    handler.startElement("", FUNCTION_SERVICE, FUNCTION_SERVICE, EMPTY);
    for (Function function : functions) {
      if (function instanceof Declarable) {
        handler.startElement("", FUNCTION, FUNCTION, EMPTY);
        generate((Declarable) function, false);
        handler.endElement("", FUNCTION, FUNCTION);
      }
    }
    handler.endElement("", FUNCTION_SERVICE, FUNCTION_SERVICE);
  }
Generates the <code>serializer-registration</code> element.
geode-core/src/main/java/org/apache/geode/internal/cache/xmlcache/CacheXmlGenerator.java