// Test with null args
args = new DeferredObject[] { new DeferredJavaObject(null), valueObj2 };
assertNull("date_add() 1st arg null", udf.evaluate(args));
args = new DeferredObject[] { valueObj1, new DeferredJavaObject(null) };
assertNull("date_add() 2nd arg null", udf.evaluate(args));
args = new DeferredObject[] { new DeferredJavaObject(null), new DeferredJavaObject(null) };
assertNull("date_add() both args null", udf.evaluate(args));
}