title: Map a JSON string into HashMap
body: <p>Considering the following JSON :</p>
  
  <pre><code>[
    {
      "map": "TEST",
      "values": [
        "test",
        "test2"
      ]
    },
    {
      "map": "TEST1",
      "values": [
        "test",
        "test3",
        "test4"
      ]
    },
    {
      "map": "TEST2",
      "values": [
        "test4",
        "test2",
        "test5",
        "test2"
      ]
    }
  ]
  </code></pre>
  
  <p>which have been loaded into a string by the getResourceAsString function.
  How can I make a HashMap where my key is "map" field, and my value is an array of "values" field ?
  I tried many solutions in other similar questions, but nothing worked.</p>
  
  <p>Here is the beginning of my code :</p>
  
  <pre><code>    ObjectMapper mapper = new ObjectMapper();
      mapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);
  </code></pre>
  
  <p>But I don't know how to assign it to a Map, readValue method doesn't seems to give the right thing</p>