update restricted headers in jdk11 client implementation (#2366)

* update restricted headers in jdk11 client implementation

* update copyright header

Author: derklaro

java11/src/main/java/feign/http2client/Http2Client.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 The Feign Authors
+ * Copyright 2012-2024 The Feign Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -203,8 +203,7 @@ private Builder newRequestBuilder(Request request, Options options) throws URISy
   static {
     // A case insensitive TreeSet of strings.
     final TreeSet<String> treeSet = new TreeSet<>(String.CASE_INSENSITIVE_ORDER);
-    treeSet.addAll(Set.of("connection", "content-length", "date", "expect", "from", "host",
-        "origin", "referer", "upgrade", "via", "warning"));
+    treeSet.addAll(Set.of("connection", "content-length", "expect", "host", "upgrade"));
     DISALLOWED_HEADERS_SET = Collections.unmodifiableSet(treeSet);
   }