Hello,
I want to include parent and children topics in my Community like this : https://releasenotes.docs.salesforce.com/en-us/winter16/release-notes/rn_networks_subtopics.htm?edition=&impact=

I used ConnectApi.ChatterGroups.createManagedTopicByName(communityId, name, managedTopicType, parentId)
communityId=my CommunityID ('0DBM0000000CajLOAS')
name=name of child topic
managedTopicType = ConnectApi.ManagedTopicType.Featured
parentId = '0TOM00000004SHDOA2'  Id of parent topic

When I run this method I have this error message: ConnectApi.ConnectApiException: Illegal value for parameter: 'parentId': 0TOM00000004SHDOA2

Can you help me?

Best regards
Anis