ImmutableAcknowledgementRequest implements AcknowledgementRequest { public static ImmutableAcknowledgementRequest getInstance(final AcknowledgementLabel acknowledgementLabel) { return new ImmutableAcknowledgementRequest(checkNotNull(acknowledgementLabel, "acknowledgementLabel")); } private  ImmutableAcknowledgementRequest(final AcknowledgementLabel label); static ImmutableAcknowledgementRequest getInstance(final AcknowledgementLabel acknowledgementLabel); @Override AcknowledgementLabel getLabel(); @Override boolean equals(@Nullable final Object o); @Override int hashCode(); @Override String toString();  }
@Test public void tryToGetInstanceWithNullAckLabel() { assertThatNullPointerException() .isThrownBy(() -> ImmutableAcknowledgementRequest.getInstance(null)) .withMessage("The acknowledgementLabel must not be null!") .withNoCause(); }