CreativeAssignment[] creativeAssignments = new CreativeAssignment[]{creativeAssignment};
rotationGroup.setCreativeAssignments(creativeAssignments);
rotationGroup.setRotationType(1);
// Assign an ad to the placement.
PlacementAssignment placementAssignment = new PlacementAssignment();
placementAssignment.setActive(true);
placementAssignment.setPlacementId(placementId);
PlacementAssignment[] placementAssignments = new PlacementAssignment[]{placementAssignment};
rotationGroup.setPlacementAssignments(placementAssignments);
// Save the rotation group.
AdSaveResult adSaveResult = service.saveAd(rotationGroup);