docs: public T header(Map<String, List<String>> headers, boolean isOverride) {
  		if(CollectionUtil.isEmpty(headers)) {
  			return (T)this;
  		}
  		
  		String name;
  		for (Entry<String, List<String>> entry : headers.entrySet()) {
  			name = entry.getKey();
  			for (String value : entry.getValue()) {
  				this.header(name, StrUtil.nullToEmpty(value), isOverride);
  			}
  		}
  		return (T)this;
  	}