From e0a101b46dac0cba172d379d89fb793dbbe44209 Mon Sep 17 00:00:00 2001
From: Carlos Sanchez <carlos@apache.org>
Date: Fri, 27 Jan 2017 10:30:34 +0100
Subject: [PATCH] Prevent NPE

Jan 27, 2017 9:15:35 AM hudson.remoting.jnlp.Main$CuiListener error
SEVERE: null
java.lang.NullPointerException
	at org.jenkinsci.remoting.engine.JnlpAgentEndpointResolver.header(JnlpAgentEndpointResolver.java:431)
	at org.jenkinsci.remoting.engine.JnlpAgentEndpointResolver.resolve(JnlpAgentEndpointResolver.java:163)
	at hudson.remoting.Engine.innerRun(Engine.java:335)
	at hudson.remoting.Engine.run(Engine.java:287)
---
 .../jenkinsci/remoting/engine/JnlpAgentEndpointResolver.java    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/jenkinsci/remoting/engine/JnlpAgentEndpointResolver.java b/src/main/java/org/jenkinsci/remoting/engine/JnlpAgentEndpointResolver.java
index fa38b6451..ba78d7d52 100644
--- a/src/main/java/org/jenkinsci/remoting/engine/JnlpAgentEndpointResolver.java
+++ b/src/main/java/org/jenkinsci/remoting/engine/JnlpAgentEndpointResolver.java
@@ -428,7 +428,7 @@ private static List<String> header(@Nonnull HttpURLConnection connection, String
         Map<String, List<String>> headerFields = connection.getHeaderFields();
         for (String headerName : headerNames) {
             for (String headerField : headerFields.keySet()) {
-                if (headerField.equalsIgnoreCase(headerName)) {
+                if (headerField != null && headerField.equalsIgnoreCase(headerName)) {
                     return headerFields.get(headerName);
                 }
             }