Populate file set property in CopyableFile for IcebergFileStreamExtractor (#4161)

Author: thisisArjit

gobblin-data-management/src/main/java/org/apache/gobblin/data/management/copy/iceberg/IcebergFileStreamExtractor.java

@@ -150,6 +150,7 @@ public Iterator<FileAwareInputStream> downloadFile(String filePath) throws IOExc
             sourcePath.getParent(), PathUtils.getRootPathChild(sourcePath), copyConfiguration);
     // Build CopyableFile using cached targetFs and copyConfiguration (initialized once in constructor)
     CopyableFile copyableFile = CopyableFile.fromOriginAndDestination(originFs, originStatus, destinationPath, this.copyConfiguration)
+        .fileSet(workUnit.getProp(ConfigurationKeys.DATASET_URN_KEY))
         .datasetOutputPath(targetFs.getUri().getPath())
         .ancestorsOwnerAndPermission(ancestorOwnerAndPermissionList)
         .build();