### Question:
ActionObserverCameraFollowUnits implements Sc2ApiSerializable<Sc2Api.ActionObserverCameraFollowUnits> { public static ActionObserverCameraFollowUnitsSyntax cameraFollowUnits() { return new Builder(); } private  ActionObserverCameraFollowUnits(Builder builder); static ActionObserverCameraFollowUnitsSyntax cameraFollowUnits(); @Override Sc2Api.ActionObserverCameraFollowUnits toSc2Api(); Set<Tag> getUnits(); @Override boolean equals(Object o); @Override int hashCode(); @Override String toString();  }### Answer:
@Test void throwsExceptionWhenUnitsAreNotSet() { assertThatExceptionOfType(IllegalArgumentException.class) .isThrownBy(() -> ((ActionObserverCameraFollowUnits.Builder) cameraFollowUnits()).build()) .withMessage("units is required"); }