private static void addMemberOperator(@NotNull GrReferenceExpression ref, @NotNull PsiField field) {
    GroovyPsiElementFactory factory = GroovyPsiElementFactory.getInstance(ref.getProject());

    GrExpression qualifier = ref.getQualifier();
    if (qualifier == null) {
      PsiClass parentClass = PsiTreeUtil.getParentOfType(ref, PsiClass.class);
      PsiClass containingClass = findContainingClass(ref, field);
      GrReferenceExpression thisRef = !ref.getManager().areElementsEquivalent(parentClass, containingClass)
                                      ? factory.createThisExpression(containingClass)
                                      : factory.createThisExpression(null);
      ref.setQualifier(thisRef);
    }

    ref.getNode().addLeaf(GroovyTokenTypes.mAT, "@", ref.getDotToken().getNode().getTreeNext());
  }
private static void addMemberOperator(@NotNull GrReferenceExpression ref, @NotNull PsiField field)