PUT test
{
  "mappings": {
    "_doc": {
      "dynamic_templates": [
        {
          "template": {
            "path_match": "prop1.prop2.*",
            "mapping": {
              "type": "keyword",
              "index": false
            }
          }
        }
      ],
      "properties": {
        "prop1": {
          "properties": {
            "prop2": {
              "type": "object",
              "dynamic": true
            }
          }
        }
      }
    }
  }
}

PUT test/_doc/1
{
  "prop1": {
    "prop2": {
      "prop3": {
        "prop4": {
          "field": "bar"
        }
      }
    }
  }
}

{
  "error": {
    "root_cause": [
      {
        "type": "mapper_parsing_exception",
        "reason": "failed to parse [prop1.prop2.prop3]"
      }
    ],
    "type": "mapper_parsing_exception",
    "reason": "failed to parse [prop1.prop2.prop3]",
    "caused_by": {
      "type": "illegal_state_exception",
      "reason": "Can't get text on a START_OBJECT at 4:16"
    }
  },
  "status": 400
}