private void registerRepoUpdateTask(RepositoryXml rxml) {
    String latest = rxml.getLatestURI();
    if (StringUtils.isBlank(latest)) {
      return;
    }

    URI uri = getURI(this, latest);

    if (null == uri) {
      LOG.warn("Could not determine how to load stack {}-{} latest definition for {}",
          stackInfo.getName(), stackInfo.getVersion(), latest);
      return;
    }

    stackContext.registerRepoUpdateTask(uri, this);
  }
Process repositories associated with the stack.
@throws AmbariException if unable to fully process the stack repositories
ambari-server/src/main/java/org/apache/ambari/server/stack/StackModule.java