### Question:
LastAggregateFunction extends DefaultAggregateFunction<Object> { @Override public AggregateBuilder<?> createAggregateBuilder() { return new LastAggregateBuilder(); }  @Override AggregateBuilder<?> createAggregateBuilder(); @Override String getFunctionName();  }### Answer:
@Test public void testBuildAggregate() throws Exception { final AggregateBuilder<?> aggregateBuilder = FUNCTION.createAggregateBuilder(); aggregateBuilder.add("1"); aggregateBuilder.add("2"); aggregateBuilder.add("3"); assertEquals("3", aggregateBuilder.getAggregate()); }