public void testRemoveFieldDoesNotDeleteReservedFields() {
DateTime time = Tools.iso8601();
Message lm = new Message("foo", "bar", time);
lm.removeField("source");
lm.removeField("timestamp");
lm.removeField("_id");
assertTrue(lm.isComplete());
assertEquals("foo", lm.getField("message"));
assertEquals("bar", lm.getField("source"));
assertEquals(time, lm.getField("timestamp"));