--- /dev/null	2016-04-22 22:42:07.067228853 +0100
+++ new/src/java.httpclient/share/classes/java/net/http/ImmutableHeaders.java	2016-04-25 23:10:54.469374344 +0100
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ */
+
+package java.net.http;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Predicate;
+
+/**
+ * Immutable HttpHeaders constructed from mutable HttpHeadersImpl.
+ */
+
+class ImmutableHeaders implements HttpHeaders {
+
+    private final Map<String,List<String>> map;
+
+    @SuppressWarnings("unchecked")
+    ImmutableHeaders() {
+        map = (Map<String,List<String>>)Collections.EMPTY_MAP;
+    }
+    // TODO: fix lower case issue. Must be lc for http/2 compares ignoreCase for http/1
+    ImmutableHeaders(HttpHeadersImpl h, Predicate<String> keyAllowed) {
+        Map<String,List<String>> src = h.directMap();
+        Map<String,List<String>> m = new HashMap<>();
+
+        src.forEach((key, value) -> {
+            if (keyAllowed.test(key))
+                m.put(key, Collections.unmodifiableList(value));
+        });
+        map = Collections.unmodifiableMap(m);
+    }
+
+    @Override
+    public Optional<String> firstValue(String name) {
+        name = name.toLowerCase();
+        List<String> l = map.get(name);
+        String v = l == null ? null : l.get(0);
+        return Optional.ofNullable(v);
+    }
+
+    @Override
+    public Optional<Long> firstValueAsLong(String name) {
+        name = name.toLowerCase();
+        return firstValue(name).map((v -> Long.parseLong(v)));
+    }
+
+    @Override
+    public List<String> allValues(String name) {
+        name = name.toLowerCase();
+        return map.get(name);
+    }
+
+    @Override
+    public Map<String, List<String>> map() {
+        return map;
+    }
+}