EMCECS
Version 4.0.0-rc.1 gives : Unrecognized field "ServerSideEncryptionEnabled" (class com.emc.object.s3.bean.Bucket)
caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "ServerSideEncryptionEnabled" (class com.emc.object.s3.bean.Bucket), not marked as ignorable (2 known properties: "Name", "CreationDate"]) at [Source: (PushbackInputStream); line: 1, column: 409] (through reference chain: com.emc.object.s3.bean.ListBucketsResult["Buckets"]->java.util.ArrayList[0]->com.emc.object.s3.bean.Bucket["ServerSideEncryptionEnabled"])
@UdayBidikar I did a test like "... ListBucketsResult result = client.listBuckets() ...", and was not able to reproduce your issue on 4.0.0-rc.1, facing ECS 3.8.0.5. However, the issue comes from Jackson, the ListBucketsResult and also Bucket class are using javax.xml.bind. That would be helpful if you can share more information, like your ECS version, Java version, code snippet.
@dunedodo my test code : ListBucketsResult rslt = s3client.listBuckets()
ECS TEST DRIVE - ECS VERSION 3.8.0.5 https://portal.ecstestdrive.com/
% java -version java version "14" 2020-03-17 Java(TM) SE Runtime Environment (build 14+36-1461) Java HotSpot(TM) 64-Bit Server VM (build 14+36-1461, mixed mode, sharing)
@UdayBidikar ECS Java SDK doesn't support Java 14 AFAIK. I think it would cause the problem here. Could you try Java 8 or 11 instead? Or wait for more Java versions support, but it's of very low priority in our roadmap with no determined ETA.