[branch 4.8] Fix compilation issue introduced by issue apache#1791

*Motivation*

when apache#1791 is cherry-picked into branch-4.8, it breaks the build.

*Changes*

Fix the compilation issue.

bookkeeper-server/src/main/java/org/apache/bookkeeper/client/LedgerHandle.java

@@ -494,6 +494,10 @@ public synchronized boolean isClosed() {
         return getLedgerMetadata().isClosed();
     }
 
+    boolean isHandleWritable() {
+        return !getLedgerMetadata().isClosed();
+    }
+
     void asyncCloseInternal(final CloseCallback cb, final Object ctx, final int rc) {
         try {
             doAsyncCloseInternal(cb, ctx, rc);