Fix possible NPE in netty client

Signed-off-by: jansupol <jan.supol@oracle.com>

connectors/netty-connector/src/main/java/org/glassfish/jersey/netty/connector/JerseyClientHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2022 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2023 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -188,6 +188,9 @@ public int read() throws IOException {
 
             if (content.isReadable()) {
                 content.retain();
+                if (nis == null) {
+                    nis = new NettyInputStream();
+                }
                 nis.publish(content);
             }