private void registerIndexedTensorDocumentType() {
        DocumentType x = new DocumentType("testindexedtensor");
        TensorType tensorType = new TensorType.Builder().indexed("x", 3).build();
        x.addField(new Field("tensorfield", new TensorDataType(tensorType)));
        types.registerDocumentType(x);
    }
Functional tests for com.yahoo.document.json.JsonWriter.

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