private @NotNull String getMirrorName() {
    String mirrorName = myMirrorName;
    if (mirrorName == null) {
      // parameter name may depend on a name of a previous one in a same parameter list
      synchronized (getParent()) {
        mirrorName = myMirrorName;
        if (mirrorName == null) {
          myMirrorName = mirrorName = calcNiceParameterName();
        }
      }
    }
    return mirrorName;
  }
private @NotNull String getMirrorName()