anchor.diff:              "ts_ms": 1520085153000,
               "txId": "6.28.807",
               "scn": 2122184,
  +            "commit_scn": 2122184,
               "snapshot": false
           },
           "op": "d",
  
positive.code:             "ts_ms": 1520085154000,
              "txId": "6.28.807",
              "scn": 2122185,
              "snapshot": false
          },
          "op": "c",
  
negative.code:                         "field": "scn"
                      },
                      {
                          "type": "int64",
                          "optional": true,
                          "field": "commit_scn"
                      },
                      {
                          "type": "boolean",
                          "optional": true,
                          "field": "snapshot"
  