BOOKKEEPER-925: Fix FindBugs discovered issues in master

sijie Fixed the other findbugs error

Author: Matteo Merli <mmerli@apache.org>

Reviewers: Guo Sijie <sijie@apache.org>

Closes #40 from merlimat/bk-925
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/ScanAndCompareGarbageCollector.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/ScanAndCompareGarbageCollector.java
index c422a89..4a4c15b 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/ScanAndCompareGarbageCollector.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/ScanAndCompareGarbageCollector.java
@@ -148,9 +148,9 @@
                 }
                 lastEnd = end;
             }
-        } catch (Exception e) {
+        } catch (Throwable t) {
             // ignore exception, collecting garbage next time
-            LOG.warn("Exception when iterating over the metadata {}", e);
+            LOG.warn("Exception when iterating over the metadata {}", t);
         } finally {
             if (zk != null) {
                 try {