/*
 * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
 * (the "License"). You may not use this work except in compliance with the License, which is
 * available at www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied, as more fully set forth in the License.
 *
 * See the NOTICE file distributed with this work for information regarding copyright ownership.
 */

package alluxio.util;

import alluxio.Configuration;
import alluxio.Constants;
import alluxio.PropertyKey;

import java.io.File;
import java.io.FileFilter;

import javax.annotation.concurrent.ThreadSafe;

/**
 * Utility functions for working with extensions.
 *
 */
@ThreadSafe
public final class ExtensionUtils {

  /**
   * List extension jars from the configured extensions directory.
   *
   * @return an array of files (one file per jar)
   */
  public static File[] listExtensions() {
    String extensionDir = Configuration.get(PropertyKey.EXTENSIONS_DIR);
    File[] extensions = new File(extensionDir).listFiles(new FileFilter() {
      public boolean accept(File file) {
        return file.getPath().toLowerCase().endsWith(Constants.EXTENSION_JAR);
      }
    });
    return extensions;
  }

  private ExtensionUtils() {} // prevent instantiation
}

@@ -822,16 +822,84 @@
 tils %7B%0A%0A
+  private static final File%5B%5D EMPTY_EXTENSIONS_LIST = new File%5B0%5D;%0A%0A
   /**%0A  
@@ -1351,16 +1351,122 @@
     %7D);%0A
+    if (extensions == null) %7B%0A      // Directory does not exist%0A      return EMPTY_EXTENSIONS_LIST;%0A    %7D%0A
     retu

Fix null ptr exception