### Question:
TimestampConstant extends TimestampFunction implements ConstantFunction { @Override public long getTimestamp(Record rec) { return value; } TimestampConstant(int position, long value); @Override long getTimestamp(Record rec);  }### Answer:
@Test public void testConstant() { TimestampConstant constant = new TimestampConstant(0, 909120909900L); Assert.assertTrue(constant.isConstant()); Assert.assertEquals(909120909900L, constant.getTimestamp(null)); }