@Before
    public void setUp() {
        documentType = new DocumentType("document1");
        field = new Field("field1", DataType.getArray(DataType.STRING));
        documentType.addField(field);
    }
NOTE: Roundtrip serialization (JSON -> DocumentUpdate -> ByteBuffer -> DocumentUpdate -> JSON) of updates is tested in DocumentUpdateJsonSerializerTest.
      Consider adding new test cases to that test class instead.

@author bratseth
document/src/test/java/com/yahoo/document/update/SerializationTestCase.java