SOLR-15162: Add some parameters to make MODIFYCOLLECTION v1 and v2 more similar. (#2402)

* expose readOnly parameter to v2 of modifycollection.


Co-authored-by: epugh@opensourceconnections.com <>

solr/CHANGES.txt

@@ -215,6 +215,8 @@ Bug Fixes
 * SOLR-14546: Fix for a relatively hard to hit issue in OverseerTaskProcessor that could lead to out of order execution
   of Collection API tasks competing for a lock (Ilan Ginzburg).
 
+* SOLR-15162: Allow readOnly parameter to be used with v2 modify collection command (Eric Pugh) 
+
 ==================  8.9.0 ==================
 
 Consult the LUCENE_CHANGES.txt file for additional, low level, changes in this release.

solr/solrj/src/resources/apispec/collections.collection.Commands.modify.json

@@ -6,6 +6,10 @@
     "replicationFactor": {
       "type": "integer",
       "description": "The number of replicas to be created for each shard. Replicas are physical copies of each shard, acting as failover for the shard. Note that changing this value on an existing collection does not automatically add more replicas to the collection. However, it will allow add-replica commands to succeed."
+    },
+    "readOnly": {
+      "type": "boolean",
+      "description": "Setting the readOnly attribute to true puts the collection in read-only mode, in which any index update requests are rejected. Other collection-level actions (e.g., adding / removing / moving replicas) are still available in this mode."
     }
 
   }