--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/internal/common/HttpHeadersImpl.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,108 @@
+/*
+ * 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
+ * questions.
+ */
+
+package jdk.incubator.http.internal.common;
+
+import jdk.incubator.http.HttpHeaders;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.OptionalLong;
+import java.util.Set;
+import java.util.TreeMap;
+
+/**
+ * Implementation of HttpHeaders.
+ */
+public class HttpHeadersImpl implements HttpHeaders {
+
+    private final TreeMap<String,List<String>> headers;
+
+    public HttpHeadersImpl() {
+        headers = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
+    }
+
+    @Override
+    public Optional<String> firstValue(String name) {
+        List<String> l = headers.get(name);
+        return Optional.ofNullable(l == null ? null : l.get(0));
+    }
+
+    @Override
+    public List<String> allValues(String name) {
+        return headers.get(name);
+    }
+
+    @Override
+    public Map<String, List<String>> map() {
+        return Collections.unmodifiableMap(headers);
+    }
+
+    public Map<String, List<String>> directMap() {
+        return headers;
+    }
+
+    // package private mutators
+
+    public HttpHeadersImpl deepCopy() {
+        HttpHeadersImpl h1 = new HttpHeadersImpl();
+        TreeMap<String,List<String>> headers1 = h1.headers;
+        Set<String> keys = headers.keySet();
+        for (String key : keys) {
+            List<String> vals = headers.get(key);
+            List<String> vals1 = new ArrayList<>(vals);
+            headers1.put(key, vals1);
+        }
+        return h1;
+    }
+
+    public void addHeader(String name, String value) {
+        headers.computeIfAbsent(name, k -> new ArrayList<>(1))
+               .add(value);
+    }
+
+    public void setHeader(String name, String value) {
+        List<String> values = new ArrayList<>(1); // most headers has one value
+        values.add(value);
+        headers.put(name, values);
+    }
+
+    @Override
+    public OptionalLong firstValueAsLong(String name) {
+        List<String> l = headers.get(name);
+        if (l == null) {
+            return OptionalLong.empty();
+        } else {
+            String v = l.get(0);
+            return OptionalLong.of(Long.parseLong(v));
+        }
+    }
+
+    public void clear() {
+        headers.clear();
+    }
+}