@lombok.Data
@DynamoDBTable(tableName)
public class Car {
   @DynamoDBHashKey(attributeName = "name")
   private carName;

   @DynamoDBRangeKey(attributeName = "model")
   private carModel;

   @DynamoDBAttribute(attributeName = "manufacturers")
   private List<Manufacturer> manufacturers;
}

public class Manufacturer {
    @DynamoDBAttribute
    private String ManufacturerName;
}

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)