title: Cannot load data from DynamoDB due to an attribute of type List<Object> which is not able to get unconverted and was saved using @DynamoDBDocument
body: <p>I am trying to save a <code>List&lt;CustomObject&gt;</code> using the @DynamoDBDocument but it gives me a DynamoDBMappingException : could not unconvert attribute.</p>
  
  <p>Here is what my Entity class looks like - </p>
  
  <pre><code>@lombok.Data
  @DynamoDBTable(tableName = "carTable")
  public class Car {
     @DynamoDBHashKey(attributeName = "name")
     private carName;
  
     @DynamoDBRangeKey(attributeName = "model")
     private carModel;
  
     @DynamoDBAttribute(attributeName = "manufacturers")
     private List&lt;Manufacturer&gt; manufacturers;
  }
  </code></pre>
  
  <p>The Manufacturer class looks like -</p>
  
  <pre><code>@lombok.Data
  @DynamoDBDocument
  public class Manufacturer {
      @DynamoDBAttribute
      private String manufacturerName;
  }
  </code></pre>
  
  <p>When using this entity and saving the values into the table it saves properly as JSON, but when retrieving it, an exception is thrown - </p>
  
  <pre><code>com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException: Car[manufacturers]; could not unconvert attribute
  at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperTableModel.unconvert(DynamoDBMapperTableModel.java:271)
  [junit]     at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.privateMarshallIntoObject(DynamoDBMapper.java:456)
  [junit]     at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.load(DynamoDBMapper.java:422)
  [junit]     at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.load(DynamoDBMapper.java:433)
  [junit]     at com.amazonaws.services.dynamodbv2.datamodeling.AbstractDynamoDBMapper.load(AbstractDynamoDBMapper.java:85)
  </code></pre>
  
  <p>What am I missing here, do I need to add some sort of TypeConverter or Marshaller here?</p>