code: @SuppressWarnings("unchecked")
      public void onLoad(ItemGroup<? extends Item> parent, String name) throws IOException {
          RunMap<RunT> _builds = createBuildRunMap();
          int max = _builds.maxNumberOnDisk();
          int next = asJob().getNextBuildNumber();
          if (next <= max) {
              LOGGER.log(Level.WARNING, "JENKINS-27530: improper nextBuildNumber {0} detected in {1} with highest build number {2}; adjusting", new Object[] {next, asJob(), max});
              asJob().updateNextBuildNumber(max + 1);
          }
          RunMap<RunT> currentBuilds = this.builds;
          if (parent != null) {
              // are we overwriting what currently exist?
              // this is primarily when Jenkins is getting reloaded
              Item current;
              try {
                  current = parent.getItem(name);
              } catch (RuntimeException x) {
                  LOGGER.log(Level.WARNING, "failed to look up " + name + " in " + parent, x);
                  current = null;
              }
              if (current != null && current.getClass() == asJob().getClass()) {
                  currentBuilds = (RunMap<RunT>) ((LazyLoadingJob) current).getLazyBuildMixIn().builds;
              }
          }
          if (currentBuilds != null) {
              // if we are reloading, keep all those that are still building intact
              for (RunT r : currentBuilds.getLoadedBuilds().values()) {
                  if (r.isBuilding()) {
                      // Do not use RunMap.put(Run):
                      _builds.put(r.getNumber(), r);
                      LOGGER.log(Level.FINE, "keeping reloaded {0}", r);
                  }
              }
          }
          this.builds = _builds;
      }
docs: Something to be called from {@link Job#onLoad}.