code: public static Set<String> listAllLinks(OperationContext context, String overlay) {
          Set<String> serverGoupNames = listServerGroupsReferencingOverlay(context.readResourceFromRoot(PathAddress.EMPTY_ADDRESS), overlay);
          Set<String> links = new HashSet<>();
          for (String serverGoupName : serverGoupNames) {
              links.addAll(listLinks(context, PathAddress.pathAddress(
                      PathElement.pathElement(SERVER_GROUP, serverGoupName),
                      PathElement.pathElement(DEPLOYMENT_OVERLAY, overlay))));
          }
          return links;
      }
docs: Returns all the deployment runtime names associated with an overlay accross all server groups.
  
  @param context the current OperationContext.
  @param overlay the name of the overlay.
  @return all the deployment runtime names associated with an overlay accross all server groups.