code: Map<String, String> packageNameMap() {
          if (packageNames == null) {
              return emptyMap();
          }
  
          Map<String, String> names = new LinkedHashMap<String, String>();
          for (PackageName name : packageNames) {
              names.put(name.getUri(), name.getPackage());
          }
          return names;
      }
docs: Returns a map of URIs to package name, as specified by the packageNames
  parameter.