Leader indices are not automatically re-followed after a full reindex

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.2.X
• Fix Version/s: 7.2.10 DXP FP5, 7.2.10.2 DXP SP2, 7.2.X
• Component/s: Search Infrastructure
• Labels:
  • liferay-dxp-72-sp2
  • liferay-fixpack-dxp-5-7210
  • marketplace-portal-search-elasticsearch7-3.0.1-7210
• Branch Version/s:
  7.2.x
• Backported to Branch:
  Committed
• Fix Priority: 4
• Epic Link: Elasticsearch Cross Cluster Replication
• Sprint: Search|S03 Sprint 13| 3.16-4.6
• Git Pull Request: https://github.com/liferay/liferay-portal-ee/pull/18571

 This is not reproducible on master as of 69091b801c451278c05db8c0f022568ab8a91497

Steps to reproduce:

1. Deploy the Elasticsearch 7 connector to the bundle by running the following command from your portal root directory: "ant -f build-test-elasticsearch7.xml deploy-elasticsearch7"
2. Add "com.liferay.portal.search.tuning.rankings.web" to the blacklist config file in osgi/configs
3. Set up two Elasticsearch clusters for CCR by running the following command from your portal root directory: "ant -f build-test-elasticsearch7.xml start-elasticsearch -Dremote.elasticsearch.ccr.enabled=true"
4. Start up portal
5. Connect the Elasticsearch clusters and create follow indices by running the following command from your portal root directory: "ant -f build-test-elasticsearch7.xml create-follower-indices"
6. Navigate to Control Panel > System Settings > Search > Cross-Cluster Replication
7. Set the following and click "Save":
   1. Check the "Enabled" checkbox
   2. Cluster Name: LiferayElasticsearchClusterTwo
   3. Transport Addresses: localhost:9500
8. Create a Web Content Article titled "Doc 1"
9. Search for "doc" and assert "Doc 1" is returned as a search result
10. Navigate to Control Panel > Configuration > Search
11. Reindex all search indexes
12. Create a Web Content Article titled "Doc 2"
13. Search for "doc"

Expected result:
Expected the leader indices to be automatically re-followed after a full reindex.
Expected "Doc 2" to be replicated to the local cluster and searchable.

Actual result:
The leader indices are not automatically re-followed.
Only "Doc 1" is returned as a search result.

Reproduced on:
Tomcat 9.0.17 + MySQL 5.7
Portal 7.2.x GIT ID: fe561f322b46dd77423b0a674e33974a08ffcebb