Merge pull request #5 from embulk/fix_ArrayIndexOutOfBoundsException_if_files_is_empty

fixed ArrayIndexOutOfBoundsException handling

Author: frsyuki

src/main/java/org/embulk/input/s3/S3FileInputPlugin.java

@@ -100,8 +100,12 @@ public ConfigDiff resume(TaskSource taskSource,
 
         List<String> files = new ArrayList<String>(task.getFiles());
         Collections.sort(files);
-        return Exec.newConfigDiff().
-            set("last_path", files.get(files.size() - 1));
+
+        ConfigDiff configDiff = Exec.newConfigDiff();
+        if (!files.isEmpty()) {
+            configDiff.set("last_path", files.get(files.size() - 1));
+        }
+        return configDiff;
     }
 
     @Override