Handles params & queryParams only if maps are not empty

Params were set in the request even if the map of params was empty, this could lead to
requests with no body even if we set one.
This commit fixes this behaviour for Netty provider.
The same has been done for queryParams (in RequestBuilderBase) to prevent '?' to be added even if not wanted

Author: rsertelon

src/main/java/com/ning/http/client/RequestBuilderBase.java

@@ -134,7 +134,7 @@ private String toUrl(boolean encode) {
                 throw new IllegalArgumentException("Illegal URL: " + url, e);
             }
 
-            if (queryParams != null) {
+            if (queryParams != null && !queryParams.isEmpty()) {
 
                 StringBuilder builder = new StringBuilder();
                 if (!url.substring(8).contains("/")) { // no other "/" than http[s]:// -> http://localhost:1234

src/main/java/com/ning/http/client/providers/netty/NettyAsyncHttpProvider.java

@@ -712,7 +712,7 @@ private static HttpRequest construct(AsyncHttpClientConfig config,
                     int length = lengthWrapper[0];
                     nettyRequest.setHeader(HttpHeaders.Names.CONTENT_LENGTH, String.valueOf(length));
                     nettyRequest.setContent(ChannelBuffers.wrappedBuffer(bytes, 0, length));
-                } else if (request.getParams() != null) {
+                } else if (request.getParams() != null && !request.getParams().isEmpty()) {
                     StringBuilder sb = new StringBuilder();
                     for (final Entry<String, List<String>> paramEntry : request.getParams()) {
                         final String key = paramEntry.getKey();