code: public static DeploymentUnit getSipContextAnchorDu(final DeploymentUnit du) {
          // attach context to top-level deploymentUnit so it can be used to get context resources (SipFactory, etc.)
          DeploymentUnit parentDu = du.getParent();
          if (parentDu == null) {
              // this is a war only deployment
              return du;
          } else if (DeploymentTypeMarker.isType(DeploymentType.EAR, parentDu)) {
              return parentDu;
          } else {
              logger.error("Can't find proper anchor deployment unit for " + du.getName() + " - This is probably a bug");
              return null;
          }
      }
docs: returns the anchor deployment unit that will have attached a SIPWebContext