Fix javadoc for LedgerMetadata's method getAllEnsembles (#2556)

diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/client/api/LedgerMetadata.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/client/api/LedgerMetadata.java
index bc18c6e..91f736f 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/client/api/LedgerMetadata.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/client/api/LedgerMetadata.java
@@ -134,9 +134,9 @@
     List<BookieId> getEnsembleAt(long entryId);
 
     /**
-     * Returns all the ensembles of this entry.
+     * Returns all the ensembles of this ledger.
      *
-     * @return all the ensembles of this entry.
+     * @return all the ensembles of this ledger.
      */
     NavigableMap<Long, ? extends List<BookieId>> getAllEnsembles();