439788 - CORS filter headers gone between 9.2.0.M0 and 9.2.1 .v20140609 for ProxyServlet requests.

Removed the offending code that was added only to avoid duplicate
Date headers, but sending of those headers is configurable from
HttpConfiguration.

jetty-proxy/src/main/java/org/eclipse/jetty/proxy/ProxyServlet.java

@@ -517,10 +517,6 @@ public class ProxyServlet extends HttpServlet
 
     protected void onResponseHeaders(HttpServletRequest request, HttpServletResponse response, Response proxyResponse)
     {
-        // Clear the response headers in case it comes with predefined ones.
-        for (String name : response.getHeaderNames())
-            response.setHeader(name, null);
-
         for (HttpField field : proxyResponse.getHeaders())
         {
             String headerName = field.getName();

jetty-proxy/src/test/java/org/eclipse/jetty/proxy/ProxyServletTest.java

@@ -32,6 +32,7 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
 import java.util.Arrays;
+import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -44,8 +45,14 @@ import java.util.zip.GZIPOutputStream;
 import javax.servlet.AsyncContext;
 import javax.servlet.AsyncEvent;
 import javax.servlet.AsyncListener;
+import javax.servlet.DispatcherType;
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
 import javax.servlet.ServletException;
 import javax.servlet.ServletOutputStream;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
 import javax.servlet.http.Cookie;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
@@ -67,6 +74,7 @@ import org.eclipse.jetty.server.HttpConfiguration;
 import org.eclipse.jetty.server.HttpConnectionFactory;
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.servlet.FilterHolder;
 import org.eclipse.jetty.servlet.ServletContextHandler;
 import org.eclipse.jetty.servlet.ServletHolder;
 import org.eclipse.jetty.toolchain.test.MavenTestingUtils;
@@ -102,6 +110,7 @@ public class ProxyServletTest
     private HttpClient client;
     private Server proxy;
     private ServerConnector proxyConnector;
+    private ServletContextHandler proxyContext;
     private ProxyServlet proxyServlet;
     private Server server;
     private ServerConnector serverConnector;
@@ -121,16 +130,18 @@ public class ProxyServletTest
         proxy = new Server();
 
         HttpConfiguration configuration = new HttpConfiguration();
+        configuration.setSendDateHeader(false);
+        configuration.setSendServerVersion(false);
         String value = initParams.get("outputBufferSize");
         if (value != null)
             configuration.setOutputBufferSize(Integer.valueOf(value));
         proxyConnector = new ServerConnector(proxy, new HttpConnectionFactory(configuration));
         proxy.addConnector(proxyConnector);
 
-        ServletContextHandler proxyCtx = new ServletContextHandler(proxy, "/", true, false);
+        proxyContext = new ServletContextHandler(proxy, "/", true, false);
         ServletHolder proxyServletHolder = new ServletHolder(proxyServlet);
         proxyServletHolder.setInitParameters(initParams);
-        proxyCtx.addServlet(proxyServletHolder, "/*");
+        proxyContext.addServlet(proxyServletHolder, "/*");
 
         proxy.start();
 
@@ -1054,5 +1065,41 @@ public class ProxyServletTest
         Assert.assertEquals(0, destination.getConnectionPool().getIdleConnections().size());
     }
 
+    @Test
+    public void testResponseHeadersAreNotRemoved() throws Exception
+    {
+        prepareProxy();
+        proxyContext.stop();
+        final String headerName = "X-Test";
+        final String headerValue = "test-value";
+        proxyContext.addFilter(new FilterHolder(new Filter()
+        {
+            @Override
+            public void init(FilterConfig filterConfig) throws ServletException
+            {
+            }
+
+            @Override
+            public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
+            {
+                ((HttpServletResponse)response).addHeader(headerName, headerValue);
+                chain.doFilter(request, response);
+            }
+
+            @Override
+            public void destroy()
+            {
+            }
+        }), "/*", EnumSet.of(DispatcherType.REQUEST));
+        proxyContext.start();
+        prepareServer(new EmptyHttpServlet());
+
+        HttpClient client = prepareClient();
+        ContentResponse response = client.newRequest("localhost", serverConnector.getLocalPort()).send();
+
+        Assert.assertEquals(200, response.getStatus());
+        Assert.assertEquals(headerValue, response.getHeaders().get(headerName));
+    }
+
     // TODO: test proxy authentication
 }