title: Jackson Exception when parsing Yaml with a Map of List values
body: <p>I have a Yaml document that includes map entries that correspond to lists.  Here's an example:</p>
  
  <pre><code>environments:
    qa: [ 'us-east-1' ]
    staging: [ 'us-east-1', 'us-west-2' ]
  </code></pre>
  
  <p>I am using Jackson 2.3.2 to parse the document into a class using the following field &amp; accessors:</p>
  
  <pre><code>private Map&lt;String, List&lt;String&gt;&gt; environments = new HashMap&lt;String, List&lt;String&gt;&gt;();
  
  @JsonProperty
  public Map&lt;String, List&lt;String&gt;&gt; getEnvironments() {
      return environments;
  }
  
  @JsonProperty
  public void setEnvironments(Map&lt;String, List&lt;String&gt;&gt; environments) {
      this.environments = environments;
  }
  </code></pre>
  
  <p>I'm testing the reading of the Yaml file with the following:</p>
  
  <pre><code>inputStream = new FileInputStream("src/test/resources/configuration_test.yml");
  config = mapper.readValue(inputStream, MyConfiguration.class);
  </code></pre>
  
  <p>The following exception is thrown with a stacktrace that's not particularly helpful:</p>
  
  <pre><code>Caused by: java.lang.IllegalArgumentException: Can not find a deserializer for non-concrete Collection type [collection type; class com.google.common.collect.ImmutableList, contains [simple type, class io.dropwizard.metrics.ReporterFactory]]
  at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory.createCollectionDeserializer(BasicDeserializerFactory.java:814)
  at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer2(DeserializerCache.java:392)
  at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer(DeserializerCache.java:350)
  at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:263)
  ... 42 more
  </code></pre>
  
  <p>Any idea how to get Jackson to parse the Map value as a List?</p>