public Map<String, String> getMetaData() {
        metaData = new HashMap<>();
        Method[] methods = this.getClass().getMethods();
        for (Method method : methods) {
            try {
                String name = method.getName();
                if ((name.startsWith("get") || name.startsWith("is"))
                        && !name.equals("get")
                        && !"getClass".equals(name)
                        && Modifier.isPublic(method.getModifiers())
                        && method.getParameterTypes().length == 0
                        && isPrimitive(method.getReturnType())) {
                    int i = name.startsWith("get") ? 3 : 2;
                    String prop = StringUtils.camelToSplitName(name.substring(i, i + 1).toLowerCase() + name.substring(i + 1), ".");
                    String key;
                    Parameter parameter = method.getAnnotation(Parameter.class);
                    if (parameter != null && parameter.key().length() > 0) {
                        key = parameter.key();
                    } else {
                        key = prop;
                    }
                    // treat url and configuration differently, the value should always present in configuration though it may not need to present in url.
                    //if (method.getReturnType() == Object.class || parameter != null && parameter.excluded()) {
                    if (method.getReturnType() == Object.class) {
                        metaData.put(key, null);
                        continue;
                    }
                    Object value = method.invoke(this);
                    String str = String.valueOf(value).trim();
                    if (value != null && str.length() > 0) {
                        if (parameter != null && parameter.escaped()) {
                            str = URL.encode(str);
                        }
                        if (parameter != null && parameter.append()) {
                            String pre = String.valueOf(metaData.get(Constants.DEFAULT_KEY + "." + key));
                            if (pre != null && pre.length() > 0) {
                                str = pre + "," + str;
                            }
                            pre = String.valueOf(metaData.get(key));
                            if (pre != null && pre.length() > 0) {
                                str = pre + "," + str;
                            }
                        }
                      /*  if (prefix != null && prefix.length() > 0) {
                            key = prefix + "." + key;
                        }*/
                        metaData.put(key, str);
                    } else {
                        metaData.put(key, null);
                    }
                    // TODO check required somewhere else.
                    /*else if (parameter != null && parameter.required()) {
                        throw new IllegalStateException(this.getClass().getSimpleName() + "." + key + " == null");
                    }*/
                } else if ("getParameters".equals(name)
                        && Modifier.isPublic(method.getModifiers())
                        && method.getParameterTypes().length == 0
                        && method.getReturnType() == Map.class) {
                    Map<String, String> map = (Map<String, String>) method.invoke(this, new Object[0]);
                    if (map != null && map.size() > 0) {
//                            String pre = (prefix != null && prefix.length() > 0 ? prefix + "." : "");
                        for (Map.Entry<String, String> entry : map.entrySet()) {
                            metaData.put(entry.getKey().replace('-', '.'), entry.getValue());
                        }
                    }
                }
            } catch (Exception e) {
                System.out.println(this.getClass().getName());
                System.out.println(method.getName());
                throw new IllegalStateException(e.getMessage(), e);
            }
        }
        return metaData;
    }

  if (method.getReturnType() == Object.class) {
                        metaData.put(key, null);
                        continue;
                    }

      if (method.getReturnType() == Object.class || parameter != null && parameter.excluded()) {
                        metaData.putIfAbsent(key, null);
                        continue;
                    }