code: protected void addSiblings(Set<CmsResource> publishResources) {
  
          List<CmsResource> toAdd = Lists.newArrayList();
          for (CmsResource resource : publishResources) {
              if (!resource.getState().isUnchanged()) {
                  try {
                      List<CmsResource> changedSiblings = getCmsObject().readSiblings(
                          resource,
                          CmsResourceFilter.ALL_MODIFIED);
                      toAdd.addAll(changedSiblings);
                  } catch (CmsException e) {
                      LOG.error(e.getLocalizedMessage(), e);
                  }
              }
          }
          publishResources.addAll(toAdd);
      }
docs: Adds siblings to a set of publish resources.<p>
  
  @param publishResources the set to which siblings should be added