MirrorMaker 2 creates all combinations of herders

We are using MM2 distributed to synchronize topics from a "Central" broker down to multiple "Local" brokers. 

replica_CENTRAL->replica_OLS.enabled = true
replica_CENTRAL->replica_OLS.topics = _schemas
replica_CENTRAL->replica_OLS.replication.factor = 3

replica_CENTRAL->replica_HBG.enabled = true
replica_CENTRAL->replica_HBG.topics = _schemas
replica_CENTRAL->replica_HBG.replication.factor = 3

...

many more

...

replica_CENTRAL->replica_VIT.enabled = true
replica_CENTRAL->replica_VIT.topics = _schemas
replica_CENTRAL->replica_VIT.replication.factor = 3

replica_CENTRAL->replica_UGO.enabled = true
replica_CENTRAL->replica_UGO.topics = _schemas
replica_CENTRAL->replica_UGO.replication.factor = 3

When looking into the Mirror Maker logs, we discover that a herder is created for each combination even if we specifically don't describe a link between 2 clusters

Exemples:

[2020-11-12 08:43:30,351] INFO creating herder for replica_VIT->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:33,697] INFO creating herder for replica_CNO->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:36,020] INFO creating herder for replica_CENTRAL->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:38,508] INFO creating herder for replica_UMO->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:40,438] INFO creating herder for replica_CNO->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:42,898] INFO creating herder for replica_ARA->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:45,457] INFO creating herder for replica_TST->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:47,860] INFO creating herder for replica_UMO->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:50,248] INFO creating herder for replica_OLS->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:52,817] INFO creating herder for replica_UGO->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:54,903] INFO creating herder for replica_HBG->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:57,081] INFO creating herder for replica_OLS->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:43:59,215] INFO creating herder for replica_TST->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:01,481] INFO creating herder for replica_OLS->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:03,320] INFO creating herder for replica_CNO->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:05,337] INFO creating herder for replica_VIT->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:07,494] INFO creating herder for replica_CENTRAL->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:09,595] INFO creating herder for replica_ARA->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:12,201] INFO creating herder for replica_VLD->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:14,360] INFO creating herder for replica_HBG->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:16,490] INFO creating herder for replica_OLS->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:18,680] INFO creating herder for replica_ARA->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:20,779] INFO creating herder for replica_VLD->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:22,596] INFO creating herder for replica_CENTRAL->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:24,579] INFO creating herder for replica_VIT->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:26,076] INFO creating herder for replica_TST->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:27,868] INFO creating herder for replica_OLS->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:30,047] INFO creating herder for replica_TST->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:32,295] INFO creating herder for replica_OLS->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:33,777] INFO creating herder for replica_CNO->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:36,083] INFO creating herder for replica_CENTRAL->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:38,857] INFO creating herder for replica_ARA->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:40,629] INFO creating herder for replica_CNO->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:43,170] INFO creating herder for replica_UGO->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:45,154] INFO creating herder for replica_HBG->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:46,981] INFO creating herder for replica_UMO->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:49,042] INFO creating herder for replica_UGO->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:51,881] INFO creating herder for replica_HBG->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:54,406] INFO creating herder for replica_HBG->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:56,378] INFO creating herder for replica_TST->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:44:58,825] INFO creating herder for replica_ARA->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:00,394] INFO creating herder for replica_CNO->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:02,060] INFO creating herder for replica_UGO->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:04,513] INFO creating herder for replica_TST->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:06,071] INFO creating herder for replica_VLD->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:08,700] INFO creating herder for replica_CNO->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:10,533] INFO creating herder for replica_VIT->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:12,539] INFO creating herder for replica_CNO->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:14,749] INFO creating herder for replica_HBG->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:16,222] INFO creating herder for replica_UMO->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:18,308] INFO creating herder for replica_VIT->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:20,212] INFO creating herder for replica_HBG->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:22,618] INFO creating herder for replica_VLD->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:24,663] INFO creating herder for replica_UGO->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:26,333] INFO creating herder for replica_ARA->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:28,408] INFO creating herder for replica_CNO->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:30,480] INFO creating herder for replica_HBG->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:32,810] INFO creating herder for replica_VIT->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:34,904] INFO creating herder for replica_OLS->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:36,893] INFO creating herder for replica_UMO->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:38,364] INFO creating herder for replica_UMO->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:40,781] INFO creating herder for replica_OLS->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:43,168] INFO creating herder for replica_VIT->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:45,215] INFO creating herder for replica_CENTRAL->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:47,305] INFO creating herder for replica_UMO->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 08:45:49,331] INFO creating herder for replica_VLD->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:16,537] INFO creating herder for replica_VIT->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:20,193] INFO creating herder for replica_CNO->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:22,410] INFO creating herder for replica_CENTRAL->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:25,009] INFO creating herder for replica_UMO->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:26,949] INFO creating herder for replica_CNO->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:29,604] INFO creating herder for replica_ARA->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:32,121] INFO creating herder for replica_TST->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:34,883] INFO creating herder for replica_UMO->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:37,323] INFO creating herder for replica_OLS->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:39,755] INFO creating herder for replica_UGO->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:42,106] INFO creating herder for replica_HBG->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:44,425] INFO creating herder for replica_OLS->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:46,484] INFO creating herder for replica_TST->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:49,388] INFO creating herder for replica_OLS->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:51,300] INFO creating herder for replica_CNO->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:54,560] INFO creating herder for replica_VIT->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:00:57,861] INFO creating herder for replica_CENTRAL->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:00,673] INFO creating herder for replica_ARA->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:03,222] INFO creating herder for replica_VLD->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:05,627] INFO creating herder for replica_HBG->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:07,752] INFO creating herder for replica_OLS->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:09,947] INFO creating herder for replica_ARA->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:12,492] INFO creating herder for replica_VLD->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:14,265] INFO creating herder for replica_CENTRAL->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:16,102] INFO creating herder for replica_VIT->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:17,661] INFO creating herder for replica_TST->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:19,440] INFO creating herder for replica_OLS->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:22,479] INFO creating herder for replica_TST->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:24,830] INFO creating herder for replica_OLS->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:26,478] INFO creating herder for replica_CNO->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:29,179] INFO creating herder for replica_CENTRAL->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:31,616] INFO creating herder for replica_ARA->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:33,467] INFO creating herder for replica_CNO->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:35,816] INFO creating herder for replica_UGO->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:37,937] INFO creating herder for replica_HBG->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:40,195] INFO creating herder for replica_UMO->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:42,318] INFO creating herder for replica_UGO->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:44,688] INFO creating herder for replica_HBG->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:47,083] INFO creating herder for replica_HBG->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:49,199] INFO creating herder for replica_TST->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:51,516] INFO creating herder for replica_ARA->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:53,042] INFO creating herder for replica_CNO->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:54,575] INFO creating herder for replica_UGO->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:57,081] INFO creating herder for replica_TST->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:01:58,540] INFO creating herder for replica_VLD->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:01,584] INFO creating herder for replica_CNO->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:03,401] INFO creating herder for replica_VIT->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:05,714] INFO creating herder for replica_CNO->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:07,664] INFO creating herder for replica_HBG->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:09,246] INFO creating herder for replica_UMO->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:11,565] INFO creating herder for replica_VIT->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:13,451] INFO creating herder for replica_HBG->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:15,872] INFO creating herder for replica_VLD->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:18,094] INFO creating herder for replica_UGO->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:19,597] INFO creating herder for replica_ARA->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:21,576] INFO creating herder for replica_CNO->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:23,834] INFO creating herder for replica_HBG->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:26,410] INFO creating herder for replica_VIT->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:28,516] INFO creating herder for replica_OLS->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:30,344] INFO creating herder for replica_UMO->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:31,850] INFO creating herder for replica_UMO->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:34,094] INFO creating herder for replica_OLS->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:36,743] INFO creating herder for replica_VIT->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:38,778] INFO creating herder for replica_CENTRAL->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:40,785] INFO creating herder for replica_UMO->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:42,816] INFO creating herder for replica_VLD->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:45,225] INFO creating herder for replica_VLD->replica_CENTRAL (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:46,659] INFO creating herder for replica_ARA->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:48,729] INFO creating herder for replica_TST->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:50,722] INFO creating herder for replica_TST->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:52,387] INFO creating herder for replica_UGO->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:54,326] INFO creating herder for replica_CENTRAL->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:56,085] INFO creating herder for replica_ARA->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:57,914] INFO creating herder for replica_VLD->replica_UMO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:02:59,665] INFO creating herder for replica_ARA->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:01,717] INFO creating herder for replica_OLS->replica_VLD (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:03,832] INFO creating herder for replica_UGO->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:06,278] INFO creating herder for replica_VLD->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:08,417] INFO creating herder for replica_CENTRAL->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:10,731] INFO creating herder for replica_UGO->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:12,712] INFO creating herder for replica_TST->replica_VIT (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:15,082] INFO creating herder for replica_VIT->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:17,439] INFO creating herder for replica_VLD->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:19,800] INFO creating herder for replica_HBG->replica_UGO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:21,554] INFO creating herder for replica_UMO->replica_HBG (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:23,536] INFO creating herder for replica_VIT->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:26,041] INFO creating herder for replica_CENTRAL->replica_TST (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:28,090] INFO creating herder for replica_UGO->replica_CNO (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:30,353] INFO creating herder for replica_CENTRAL->replica_ARA (org.apache.kafka.connect.mirror.MirrorMaker)
[2020-11-12 09:03:32,826] INFO creating herder for replica_UMO->replica_OLS (org.apache.kafka.connect.mirror.MirrorMaker)

So much that we reached the limit of our user property LimitNOFILE recently when trying to add a new "Local" cluster.

I believe this behavior leads to unecessary connections and resource usage that could be easily avoided by just limiting the herder creation only to elements specifically described in the mirrormaker.properties file

https://github.com/apache/kafka/blob/trunk/connect/mirror/src/main/java/org/apache/kafka/connect/mirror/MirrorMaker.java#L130-L136