title: How to iterate a JsonElement with unknown keys on Kotlin using kotlinx?
body: <p>I'm new on Kotlin and I'm trying parse a Json file to take your values. The first problem is that I don't know the keys and the second problem is that I don't know use Kotlin perfectely. Let me explain the case.</p>
  
  <p>This is a Json format that I getting from web:</p>
  
  <pre><code>{
      "Meta Data": {
          "1. Information": "Intraday (5min) open, high, low, close prices and volume",
          "2. Symbol": "MRFG3.SA",
          "3. Last Refreshed": "2019-09-30 13:05:00",
          "4. Interval": "5min",
          "5. Output Size": "Compact",
          "6. Time Zone": "US/Eastern"
      },
      "Time Series (5min)": {
          "2019-09-30 13:05:00": {
              "1. open": "10.9400",
              "2. high": "10.9500",
              "3. low": "10.9300",
              "4. close": "10.9300",
              "5. volume": "6400"
          },
          "2019-09-30 13:00:00": {
              "1. open": "10.9600",
              "2. high": "10.9600",
              "3. low": "10.9200",
              "4. close": "10.9500",
              "5. volume": "33657"
          },
          "2019-09-30 12:55:00": {
              "1. open": "10.9705",
              "2. high": "10.9906",
              "3. low": "10.9605",
              "4. close": "10.9605",
              "5. volume": "36767"
          },
          ...
     }
  }
  </code></pre>
  
  <p>Note that keys can change by time. So far, I can get the file and print it:</p>
  
  <pre><code>import kotlinx.serialization.json.Json
  import java.net.URI
  import java.net.http.HttpClient
  import java.net.http.HttpRequest
  import java.net.http.HttpResponse
  
  fun getContent() {
      val client = HttpClient.newBuilder().build()
      val request = HttpRequest.newBuilder()
              .uri(URI.create("https://www.alphavantage.co/query?function=TIME_SERIES_INTRADAY&amp;interval=1min&amp;symbol=MRFG3.SA&amp;apikey=xxx"))
              .build()
      val response = client.send(request,HttpResponse.BodyHandlers.ofString())
      val wholeJson = Json.nonstrict.parseJson(response.body())
      println(wholeJson)
  }
  </code></pre>
  
  <p>and it's ok, the content is printed in one line correctely. So, now I want iterate on this keys like a map.iterator. How do it on Kotlin?</p>