added more comments on v1,v2,v3

Signed-off-by: Amit Galitzky <[email protected]>

src/main/java/org/opensearch/ad/ml/CheckpointDao.java

@@ -117,6 +117,14 @@ public class CheckpointDao {
 
     private Gson gson;
     private RandomCutForestMapper mapper;
+
+    // For further reference v1, v2 and v3 refer to the different variations of RCF models
+    // used by AD. v1 was originally used with the lunch of OS 1.0. We later converted to v2
+    // which included changes requiring a specific converter from v1 to v2 for BWC.
+    // v2 models are created by RCF-3.0-rc1 which can be found on maven central.
+    // v3 is the latest model version form RCF introduced by RCF-3.0-rc2.
+    // Although this version has a converter method for v2 to v3, after BWC testing it was decided that
+    // an explicit use of the converter won't be needed as the changes between the models are indeed BWC.
     private V1JsonToV3StateConverter converter;
     private ThresholdedRandomCutForestMapper trcfMapper;
     private Schema<ThresholdedRandomCutForestState> trcfSchema;