The form exported data showing empty value for 'Select from list' field

Issue

Steps to reproduce:
1. Start Liferay DXP 7.0
2. Navigate to Content > Forms > Create a new data provider.
3. Data provider entries are:
```
 Name: Countries of the World
 URL: http://localhost:8080/api/jsonws/country/get-countries/
 Displayed JSON Attribute: nameCurrentValue
 Stored JSON Attribute: name
 User Name: test@liferay.com
 Password: test
```
4. Click Save.
5. Create a form and select the 'select from list' field.
6. Choose the data provider and click save.
7. Deploy the form on a page.
8. Select any country and submit.
9. Again, navigate to form and export the form as CSV.
Actual Result: The CSV file shows the Country value as empty.
Expected Result: The exported data must show the value of the selected Country.

The observed behavior is a known Liferay DXP bug which has been addressed in Liferay DXP 7.0 SP7.
If the hotfix is required for this issue, please create a support ticket requesting the hotfix by attaching the patch details.
Installing Fix Packs and Hotfixes on Liferay DXP will guide to installation of the hotfix in the respective environment.