DDMDataProviderInstanceService didn't display properly using API

• Type: Bug
• Status: Closed
• Resolution: No Longer Reproducible
• Affects Version/s: 7.0.X
• Fix Version/s: 7.0.X
• Component/s: Dynamic Data Mapping, Forms, Security Vulnerability
• Labels: None
• Story Points: 1
• Fix Priority: 3

Steps to reproduce:

1. Go to Control Panel Site administration -> Content -> Forms, click on portlet configuration -> data providers (http://localhost:8080/group/guest/~/control_panel/manage?p_p_id=com_liferay_dynamic_data_mapping_data_provider_web_portlet_DDMDataProviderPortlet&&p_p_mode=view&_com_liferay_dynamic_data_mapping_data_provider_web_portlet_DDMDataProviderPortlet_mvcPath=%2Fedit_data_provider.jsp&_com_liferay_dynamic_data_mapping_data_provider_web_portlet_DDMDataProviderPortlet_type=rest)
2. Add a new Forms REST Data Provider and save
3. Create a new user
4. Sign in as the new user
5. Go to My Account ->Account Settings
6. Get current companyId (e.g. 20101) and p_auth (e.g. p_auth=C8reX8Nb&p_p_auth=VnXpHS4Q)
7. Go to http://localhost:8080/api/jsonws/ddm.ddmdataproviderinstance/search/company-id/20202/group-ids/[]/-keywords/start/-1/end/-1/-order-by-comparator?p_auth=C8reX8Nb&p_p_auth=VnXpHS4Q

Expected result: All the related information about ddmdataproviderinstance should be displayed in the UI.
Actual result: Only a pair of square brackets displayed in the UI.