anchor.diff:      "tweet" : {
           "properties" : {
               "image" : {
  -                "type" : "binary",
  +                "type" : "binary"
               }
           }
       }
  
positive.code: {
    "book" : {
      "properties" : {
        "title" : { "type" : "string", "copy_to" : ["meta_data", "article_info"] },
      }
  }
  --------------------------------------------------
  
negative.code:     "properties" : {
        "title" : { "type" : "string", "copy_to" : "meta_data" },
        "abstract" : { "type" : "string", "copy_to" : "meta_data" },
        "meta_data" : { "type" : "string" }
      }
  }
  --------------------------------------------------
  