I added a PR for this: #5567 
 Fixed by https://github.com/netty/netty/pull/5567

OpenSslServerContext NullPointEexception when using a KeyManagerFactory
Support for using a KeyManagerFactory with OpenSSL was added by [PR 5493](https://github.com/netty/netty/pull/5439). However, there are a couple lingering `checkNotNull()` [assertions](https://github.com/netty/netty/blob/4.1/handler/src/main/java/io/netty/handler/ssl/OpenSslServerContext.java#L352) that cause a NullPointerException when using a KeyManagerFactory instead of a certificate-chain/private-key pair.

I think it's intended that these variables can be null now since there's an `if (keyCertChain != null)` check on line 370.

handler/src/main/java/io/netty/handler/ssl/OpenSslServerContext.java
handler/src/main/java/io/netty/handler/ssl/OpenSslServerContext.java
diff --git a/handler/src/main/java/io/netty/handler/ssl/OpenSslServerContext.java b/handler/src/main/java/io/netty/handler/ssl/OpenSslServerContext.java
index 9db007a7d6b..4986388d07a 100644
--- a/handler/src/main/java/io/netty/handler/ssl/OpenSslServerContext.java
+++ b/handler/src/main/java/io/netty/handler/ssl/OpenSslServerContext.java
@@ -349,9 +349,6 @@ private OpenSslServerContext(
         // Create a new SSL_CTX and configure it.
         boolean success = false;
         try {
-            checkNotNull(keyCertChain, "keyCertChainFile");
-            checkNotNull(key, "keyFile");
-
             synchronized (OpenSslContext.class) {
                 try {
                     SSLContext.setVerify(ctx, SSL.SSL_CVERIFY_NONE, VERIFY_DEPTH);
@@ -373,9 +370,7 @@ private OpenSslServerContext(
                         }
 
                         if (keyManagerFactory != null) {
-                            X509KeyManager keyManager = chooseX509KeyManager(
-                                    buildKeyManagerFactory(keyCertChain, key, keyPassword, keyManagerFactory)
-                                            .getKeyManagers());
+                            X509KeyManager keyManager = chooseX509KeyManager(keyManagerFactory.getKeyManagers());
                             keyMaterialManager = useExtendedKeyManager(keyManager) ?
                                     new OpenSslExtendedKeyMaterialManager(
                                             (X509ExtendedKeyManager) keyManager, keyPassword) :
