WFLY-2681 Send correct content type from management REST API

Also fix some Undertow usage to be more correct/efficent

domain-http/interface/src/main/java/org/jboss/as/domain/http/server/Common.java

@@ -78,7 +78,7 @@ private static void sendError(HttpServerExchange exchange, boolean encode, Model
                 response.writeBase64(bout);
                 byte[] bytes = bout.toByteArray();
 
-                exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, APPLICATION_DMR_ENCODED+ ";" + UTF_8);
+                exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, APPLICATION_DMR_ENCODED+ "; charset=" + UTF_8);
                 exchange.getResponseHeaders().put(Headers.CONTENT_LENGTH, String.valueOf(bytes.length));
                 exchange.setResponseCode(errorCode);
 
@@ -103,7 +103,7 @@ private static void sendError(HttpServerExchange exchange, boolean encode, Model
 
             String msgString = stringWriter.toString();
             byte[] bytes = msgString.getBytes();
-            exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, TEXT_PLAIN + ";" + UTF_8);
+            exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, TEXT_PLAIN + "; charset=" + UTF_8);
             exchange.getResponseHeaders().put(Headers.CONTENT_LENGTH, String.valueOf(bytes.length));
             exchange.setResponseCode(errorCode);
 

domain-http/interface/src/main/java/org/jboss/as/domain/http/server/DomainApiUploadHandler.java

@@ -103,16 +103,16 @@ public void handleRequest(HttpServerExchange exchange) throws Exception {
     }
 
     static void writeResponse(HttpServerExchange exchange, ModelNode response, String contentType) {
-        exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, contentType  + ";" + Common.UTF_8);
+        exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, contentType  + "; charset=" + Common.UTF_8);
         exchange.setResponseCode(200);
 
         //TODO Content-Length?
+        exchange.startBlocking();
 
-        PrintWriter print = new PrintWriter(new ChannelOutputStream(exchange.getResponseChannel()));
+        PrintWriter print = new PrintWriter(exchange.getOutputStream());
         try {
             response.writeJSONString(print, true);
         } finally {
-            print.flush();
             IoUtils.safeClose(print);
         }
     }

domain-http/interface/src/main/java/org/jboss/as/domain/http/server/DomainUtil.java

@@ -30,6 +30,7 @@
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.PrintWriter;
+import java.nio.ByteBuffer;
 
 import io.undertow.server.HttpServerExchange;
 import io.undertow.util.HeaderMap;
@@ -52,59 +53,35 @@ public static void writeResponse(final HttpServerExchange exchange, final int st
 
         final HeaderMap responseHeaders = exchange.getResponseHeaders();
         final String contentType = operationParameter.isEncode() ? Common.APPLICATION_DMR_ENCODED : Common.APPLICATION_JSON;
-        responseHeaders.put(Headers.CONTENT_TYPE, contentType + ";" + Common.UTF_8);
+        responseHeaders.put(Headers.CONTENT_TYPE, contentType + "; charset=" + Common.UTF_8);
 
         writeCacheHeaders(exchange, status, operationParameter);
 
         if (operationParameter.isGet() && status == 200) {
             // For GET request the response is purley the model nodes result. The outcome
             // is not send as part of the response but expressed with the HTTP status code.
             response = response.get(RESULT);
-            try {
-                int length = getResponseLength(response, operationParameter);
-                responseHeaders.put(Headers.CONTENT_LENGTH, length);
-            } catch (IOException e) {
-                ROOT_LOGGER.errorf(e, "Unable to get length for '%s'", operationParameter);
-            }
         }
-
-        OutputStream out = new ChannelOutputStream(exchange.getResponseChannel());
-        PrintWriter print = new PrintWriter(out);
         try {
-            try {
-                if (operationParameter.isEncode()) {
-                    response.writeBase64(out);
-                } else {
-                    response.writeJSONString(print, !operationParameter.isPretty());
-                }
-            } finally {
-                print.flush();
-                try {
-                    out.flush();
-                } finally {
-                    IoUtils.safeClose(print);
-                    IoUtils.safeClose(out);
-                }
-            }
+            byte[] data = getResponseBytes(response, operationParameter);
+            responseHeaders.put(Headers.CONTENT_LENGTH, data.length);
+            exchange.getResponseSender().send(ByteBuffer.wrap(data));
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
     }
 
-    private static int getResponseLength(final ModelNode modelNode, final OperationParameter operationParameter) throws IOException {
-        int length;
+    private static byte[] getResponseBytes(final ModelNode modelNode, final OperationParameter operationParameter) throws IOException {
         if (operationParameter.isEncode()) {
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
             BufferedOutputStream out = new BufferedOutputStream(baos);
             modelNode.writeBase64(out);
             out.flush();
-            length = baos.size();
-            IoUtils.safeClose(out, baos);
+            return baos.toByteArray();
         } else {
             String json = modelNode.toJSONString(!operationParameter.isPretty());
-            length = json.length();
+            return json.getBytes(Common.UTF_8);
         }
-        return length;
     }
 
     public static void writeCacheHeaders(final HttpServerExchange exchange, final int status, final OperationParameter operationParameter) {