### Question:
JdbcHighWaterMarkAccumulableParam implements AccumulableParam<JdbcHighWaterMark, Long>, Serializable { @Nonnull @Override public JdbcHighWaterMark addInPlace(@Nonnull final JdbcHighWaterMark left, @Nonnull final JdbcHighWaterMark right) { left.accumulate(right.getValue()); return left; }  @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 addInPlace() { final JdbcHighWaterMark left = new JdbcHighWaterMark(); left.accumulate(1L); final JdbcHighWaterMark right = new JdbcHighWaterMark(); right.accumulate(2L); final JdbcHighWaterMark result = new JdbcHighWaterMarkAccumulableParam().addInPlace(left, right); Assert.assertEquals(new Long(2L), result.getValue()); Assert.assertEquals(left, result); }