anchor.diff:  ------------------------------------------
   PUT /_search/template/my_template
   {
  -    "template": { "match": { "text": "{query_string}" }}},
  +    "template": { "match": { "text": "{{query_string}}" }}},
   }
   ------------------------------------------
   
  
positive.code: {
      "query": {
          "template": {
              "query": "{ \"match\": { \"text\": \"{query_string}\" }}}", <1>
              "params" : {
                  "query_string" : "all about search"
              }
  
negative.code: {
      "query": {
          "template": {
              "query": { "match": { "text": "{{query_string}}" }}},
              "params" : {
                  "query_string" : "all about search"
              }
  