anchor.diff:    /// logs.
     ///
     /// The returned map will be mutated.
  +  @protected
     void registerServiceExtension({
       @required String name,
       @required ServiceExtensionCallback callback
  
positive.code:   ///
    /// Calls the `setter` callback with the new value when the
    /// service extension method is called with a new value.
    void registerBoolServiceExtension({
      String name,
      @required ValueGetter<bool> getter,
  
negative.code:   /// See also:
    ///
    ///  * <https://github.com/dart-lang/sdk/blob/master/runtime/vm/service/service.md#rpcs-requests-and-responses>
    @protected
    @mustCallSuper
    void initServiceExtensions() {
      assert(!_debugServiceExtensionsRegistered);
      registerSignalServiceExtension(
  