code: public ConverterRegistry putCustom(Type type, Converter<?> converter) {
  		if (null == customConverterMap) {
  			synchronized (this) {
  				if (null == customConverterMap) {
  					customConverterMap = new ConcurrentHashMap<>();
  				}
  			}
  		}
  		customConverterMap.put(type, converter);
  		return this;
  	}
docs: 登记自定义转换器
  
  @param type 转换的目标类型
  @param converter 转换器
  @return {@link ConverterRegistry}