private void registerSetDocumentType() {
        DocumentType x = new DocumentType("testset");
        DataType d = new WeightedSetDataType(DataType.STRING, true, true);
        x.addField(new Field("actualset", d));
        types.registerDocumentType(x);
    }
Functional tests for com.yahoo.document.json.JsonWriter.

@author Steinar Knutsen
document/src/test/java/com/yahoo/document/json/JsonWriterTestCase.java