--- a/jdk/src/share/classes/sun/net/www/protocol/http/HttpURLConnection.java	Tue Jan 10 17:46:46 2012 -0800
+++ b/jdk/src/share/classes/sun/net/www/protocol/http/HttpURLConnection.java	Wed Jan 11 10:52:25 2012 +0000
@@ -2633,8 +2633,7 @@
         if (filteredHeaders != null)
             return filteredHeaders;
 
-        filteredHeaders = new HashMap<>();
-        Map<String, List<String>> headers;
+        Map<String, List<String>> headers, tmpMap = new HashMap<>();
 
         if (cachedHeaders != null)
             headers = cachedHeaders.getHeaders();
@@ -2650,11 +2649,10 @@
                     filteredVals.add(fVal);
             }
             if (!filteredVals.isEmpty())
-                filteredHeaders.put(key,
-                                    Collections.unmodifiableList(filteredVals));
+                tmpMap.put(key, Collections.unmodifiableList(filteredVals));
         }
 
-        return filteredHeaders;
+        return filteredHeaders = Collections.unmodifiableMap(tmpMap);
     }
 
     /**

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/net/HttpURLConnection/UnmodifiableMaps.java	Wed Jan 11 10:52:25 2012 +0000
@@ -0,0 +1,149 @@
+/*
+ * Copyright (c) 2012, 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.
+ *
+ * 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.
+ */
+
+/**
+ * @test
+ * @bug 7128648
+ * @summary HttpURLConnection.getHeaderFields should return an unmodifiable Map
+ */
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.URI;
+import java.net.HttpURLConnection;
+import java.util.Collection;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import com.sun.net.httpserver.HttpExchange;
+import com.sun.net.httpserver.HttpHandler;
+import com.sun.net.httpserver.HttpServer;
+import com.sun.net.httpserver.Headers;
+
+public class UnmodifiableMaps {
+
+    void test(String[] args) throws Exception {
+        HttpServer server = startHttpServer();
+        try {
+            InetSocketAddress address = server.getAddress();
+            URI uri = new URI("http://" + InetAddress.getLocalHost().getHostAddress()
+                              + ":" + address.getPort() + "/foo");
+            doClient(uri);
+        } finally {
+            server.stop(0);
+        }
+    }
+
+    void doClient(URI uri) throws Exception {
+        HttpURLConnection uc = (HttpURLConnection) uri.toURL().openConnection();
+
+        // Test1: getRequestProperties is unmodifiable
+        System.out.println("Check getRequestProperties");
+        checkUnmodifiable(uc.getRequestProperties());
+        uc.addRequestProperty("X", "V");
+        uc.addRequestProperty("X1", "V1");
+        checkUnmodifiable(uc.getRequestProperties());
+
+        int resp = uc.getResponseCode();
+        check(resp == 200,
+              "Unexpected response code. Expected 200, got " + resp);
+
+        // Test2: getHeaderFields is unmodifiable
+        System.out.println("Check getHeaderFields");
+        checkUnmodifiable(uc.getHeaderFields());
+        // If the implementation does caching, check again.
+        checkUnmodifiable(uc.getHeaderFields());
+    }
+
+    // HTTP Server
+    HttpServer startHttpServer() throws IOException {
+        HttpServer httpServer = HttpServer.create(new InetSocketAddress(0), 0);
+        httpServer.createContext("/foo", new SimpleHandler());
+        httpServer.start();
+        return httpServer;
+    }
+
+    class SimpleHandler implements HttpHandler {
+        @Override
+        public void handle(HttpExchange t) throws IOException {
+            Headers respHeaders = t.getResponseHeaders();
+            // ensure some response headers, over the usual ones
+            respHeaders.add("RespHdr1", "Value1");
+            respHeaders.add("RespHdr2", "Value2");
+            respHeaders.add("RespHdr3", "Value3");
+            t.sendResponseHeaders(200, -1);
+            t.close();
+        }
+    }
+
+    void checkUnmodifiable(Map<String,List<String>> map) {
+        checkUnmodifiableMap(map);
+
+        // Now check the individual values
+        Collection<List<String>> values = map.values();
+        for (List<String> value : values) {
+            checkUnmodifiableList(value);
+        }
+    }
+
+    void checkUnmodifiableMap(final Map<String,List<String>> map) {
+        expectThrow( new Runnable() {
+            public void run() { map.clear(); }});
+        expectThrow( new Runnable() {
+            public void run() { map.put("X", new ArrayList<String>()); }});
+        expectThrow( new Runnable() {
+            public void run() { map.remove("X"); }});
+    }
+
+    void checkUnmodifiableList(final List<String> list) {
+        expectThrow( new Runnable() {
+            public void run() { list.clear(); }});
+        expectThrow( new Runnable() {
+            public void run() { list.add("X"); }});
+        expectThrow( new Runnable() {
+            public void run() { list.remove("X"); }});
+    }
+
+    void expectThrow(Runnable r) {
+        try { r.run(); fail("Excepted UOE to be thrown."); Thread.dumpStack(); }
+        catch (UnsupportedOperationException e) { pass(); }
+    }
+
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++;}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond, String failMessage) {if (cond) pass(); else fail(failMessage);}
+    public static void main(String[] args) throws Throwable {
+        Class<?> k = new Object(){}.getClass().getEnclosingClass();
+        try {k.getMethod("instanceMain",String[].class)
+                .invoke( k.newInstance(), (Object) args);}
+        catch (Throwable e) {throw e.getCause();}}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}
+