feature introduction

1. Change the contents of properties in mapping to struct, as follows

{
    "mappings": {
        "properties": {
            "doc_id": {
                "type": "keyword"
            },
            "id": {
                "type": "long"
            },
            "path": {
                "type": "keyword"
            },
            "name": {
                "type": "text"
            },
            "url": {
                "type": "keyword"
            },
            "description": {
                "type": "text"
            },
            "created_time": {
                "type": "date",
                "format": "yyyy-MM-dd HH:mm:ss"
            }
        }
    }
}

After treatment

message Es2StructTmp {
  string created_time = 1;
  string description = 2;
  string doc_id = 3;
  int32 id = 4;
  string name = 5;
  string path = 6;
  string url = 7;
}