public ExtensionInfo getExtension(String name) {
    Collection<ExtensionInfo> extensions = getExtensions();
    for (ExtensionInfo extension : extensions) {
      if (extension.getName().equals(name)) {
        return extension;
      }
    }
    //todo: exception?
    return null;
  }
@return A list containing all repos for this stack, grouped by os
ambari-server/src/main/java/org/apache/ambari/server/state/StackInfo.java