SSDM-12929: readSymbolicLink throws a NoSuchFileException (instead of...

SSDM-12929: readSymbolicLink throws a NoSuchFileException (instead of UnsupportedOperationException) in order to be translated into a status the (S)FTP client can deal with.

server-original-data-store/source/java/ch/systemsx/cisd/openbis/dss/generic/server/ftp/FtpServer.java

@@ -29,6 +29,7 @@ import java.nio.file.DirectoryStream.Filter;
 import java.nio.file.FileStore;
 import java.nio.file.FileSystem;
 import java.nio.file.LinkOption;
+import java.nio.file.NoSuchFileException;
 import java.nio.file.OpenOption;
 import java.nio.file.Path;
 import java.nio.file.ProviderMismatchException;
@@ -484,6 +485,12 @@ public class FtpServer implements FileSystemFactory, org.apache.sshd.common.file
             this.fileSystemView = fileSystemView;
         }
 
+        @Override
+        public Path readSymbolicLink(Path link) throws IOException
+        {
+            throw new NoSuchFileException("Symbolic links are not supported: " + link);
+        }
+
         @Override
         public String getScheme()
         {