Convert to JSON class objects that recur reference

Question

I am trying to convert to JSON two lists of dististe classes.

public class CustomerItem implements Parcelable {
    //...
    private List<ProductItem> mProductList = new ArrayList<>();
...
}

public class ProductItem implements Parcelable {
   //...
    private List<String> mCustomerList;
//...
}

And I have the following function onPause():

@Override
    protected void onPause() {
        Gson gson = new Gson();
        mJSONProducts = gson.toJson(mBillAccount.getProductItemList());
        mJSONCustomers = gson.toJson(mBillAccount.getCustomerItemList());
        //mBillAccount é objeto da classe BillAccount, que contém as duas listas como membro
        mEditor.putString(KEY_PRODUCT_LIST, mJSONProducts);
        mEditor.putString(KEY_CUSTOMER_LIST, mJSONCustomers);
        /...
        mEditor.apply();
        super.onPause();
    }

Within my function onPause(), i convert the lists with the method gson.toJson(), to be able to rescue them when restarting the app. At this moment, according to the memory usage monitor, the app is increasingly consuming the memory of the phone.

With the use of Debugger, I noticed that no value pass is ever invoked with the method mJSONCustomers = gson.toJson(mBillAccount.getCustomerItemList()); When reopening the app, the GUI freezes (I believe it freezes because it is still trying to generate JSON). When opening memory usage monitor, I noticed that from that instant the app gradually consumes the disk memory. I can give up saving the limb mCustomerList. I tried using the notation @Expose(serialize = false, deserialize = false) on this member, but also failed to work.

EDITION: When I asked the question, I believed it was a cyclical recursion, as if mCustomerList classmate List<CustomerItem> instead of List<String>. It was my lack of attention. mCustomerList is of class List<String>. So I believe the problem is not cyclical recursion as I stated earlier. I apologize for the confusion.