kv in painless

kv.json

POST _ingest/pipeline/_simulate
{
  "pipeline" : {
  "description": "A pipeline to do named entity extraction",
  "processors": [
    {
      "script": {
        "lang": "painless",
        "inline": "ctx.params = [:] ; /&/.splitAsStream(ctx.x).forEach(pair -> { def x = /=/.split(pair); ctx.params[x[0]] = x[1]; })"
      }
    }
  ]
  },
  "docs" : [
    { "_source": { "x":"a=b&c=d&e=f"}}
  ]
}