I send following data to Logstash:
{
"a": 1,
"b": 2,
"c": 3,
"d": {
      ["key": "felan", "value": 123], ["key": "bahman", "value":321]
    }
}
I want to convert it to:
{
"a": 1,
"b": 2,
"c": 3,
"d": {
      "felan": 123, 
      "bahman": 321
    }
}
How should I write the filter in Logstash?