From cce4a5b4d9dc9715ceb632adfa93540e81d22134 Mon Sep 17 00:00:00 2001
From: Satish Duggana <satishd@apache.org>
Date: Thu, 18 Jan 2018 09:13:38 +0530
Subject: [PATCH] STORM-2900 Always return non null collection for config keys
 in AbstractHadoopNimbusPluginAutoCreds.

---
 .../storm/common/AbstractHadoopNimbusPluginAutoCreds.java     | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/external/storm-autocreds/src/main/java/org/apache/storm/common/AbstractHadoopNimbusPluginAutoCreds.java b/external/storm-autocreds/src/main/java/org/apache/storm/common/AbstractHadoopNimbusPluginAutoCreds.java
index 6f76b9f3eba..83e6d9b8399 100644
--- a/external/storm-autocreds/src/main/java/org/apache/storm/common/AbstractHadoopNimbusPluginAutoCreds.java
+++ b/external/storm-autocreds/src/main/java/org/apache/storm/common/AbstractHadoopNimbusPluginAutoCreds.java
@@ -31,6 +31,7 @@
 import javax.xml.bind.DatatypeConverter;
 import java.nio.file.Paths;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -121,7 +122,8 @@ protected void fillHadoopConfiguration(Map topologyConf, String configKey, Confi
 
     protected List<String> getConfigKeys(Map conf) {
         String configKeyString = getConfigKeyString();
-        return (List<String>) conf.get(configKeyString);
+        List<String> configKeys = (List<String>) conf.get(configKeyString);
+        return configKeys != null ? configKeys : Collections.emptyList();
     }
 
 }