Elastic search, field name starting with a

I am using elasticsearch 1.3.4 and groovy. What I am trying to do is use a script in an elastic search query:

{
  "size": 0,
  "query": {
    "bool": {
      "must": [
        {
          "range": {
            "@timestamp": {
              "gte": "2014-12-08T03:40:00.000Z",
              "lte": "2014-12-08T03:40:59.999Z"
            }
          }
        }
      ],
      "must_not": []
    }
  },
  "facets": {
    "myFacet": {
      "terms": {
        "script": "doc['@field1'].value + ':' + doc['@field2'].value"
      }
    }
  }
}

      

        
        
        
      

    

For some reason, the field name starts with at. The problem is that groovy treats the at sign as a special character ( http://groovy.codehaus.org/Operators ). Error messages from groovy:

nested: GroovyScriptCompilationException [MultipleCompilationErrorsException [autoload completed: \ nScript78.groovy: 1: cannot resolve class field, cannot find class for annotation \ n @

... Is it possible to make groovy work with a field that starts with the "@" sign?