### Question:
JdbcHighWaterMarkAccumulableParam implements AccumulableParam<JdbcHighWaterMark, Long>, Serializable { @Nonnull @Override public JdbcHighWaterMark addAccumulator(@Nonnull final JdbcHighWaterMark accumulator, @Nullable final Long value) { accumulator.accumulate(value); return accumulator; }  @Nonnull @Override JdbcHighWaterMark addAccumulator(@Nonnull final JdbcHighWaterMark accumulator, @Nullable final Long value); @Nonnull @Override JdbcHighWaterMark addInPlace(@Nonnull final JdbcHighWaterMark left, @Nonnull final JdbcHighWaterMark right); @Nonnull @Override JdbcHighWaterMark zero(@Nonnull final JdbcHighWaterMark template);  }### Answer:
@Test public void addAccumulator() { final JdbcHighWaterMark highWaterMark = new JdbcHighWaterMark(); final JdbcHighWaterMarkAccumulableParam param = new JdbcHighWaterMarkAccumulableParam(); param.addAccumulator(highWaterMark, 1L); Assert.assertEquals(new Long(1L), highWaterMark.getValue()); param.addAccumulator(highWaterMark, 2L); Assert.assertEquals(new Long(2L), highWaterMark.getValue()); }