private @Nullable PsiMethod calcSourceMirrorMethod() {
    PsiClass mirrorClass = ((ClsClassImpl)getParent()).getSourceMirrorClass();
    if (mirrorClass != null) {
      for (PsiMethod sourceMethod: mirrorClass.findMethodsByName(getName(), false)) {
        if (MethodSignatureUtil.areParametersErasureEqual(this, sourceMethod)) {
          return sourceMethod;
        }
      }
    }
    return null;
  }
private @Nullable PsiMethod calcSourceMirrorMethod()