code: public String getAppInfo(ClusterNode node, ResourceType type) {
      Map<ResourceType, String> resourceInfos = nameToApps.get(node.getName());
      if (resourceInfos == null) {
        return null;
      } else {
        return resourceInfos.get(type);
      }
    }
docs: Get information about applications running on a node.
  @param node The node.
  @param type The type of resources.
  @return The application-specific information