Fix for AsyncHttpClient#407.

Author: rlubke

providers/grizzly/src/main/java/org/asynchttpclient/providers/grizzly/bodyhandler/BodyGeneratorBodyHandler.java

@@ -44,7 +44,7 @@ public boolean doHandle(final FilterChainContext ctx,
         final BodyGenerator generator = request.getBodyGenerator();
         final Body bodyLocal = generator.createBody();
         final long len = bodyLocal.getContentLength();
-        if (len > 0) {
+        if (len >= 0) {
             requestPacket.setContentLengthLong(len);
         } else {
             requestPacket.setChunked(true);

providers/grizzly/src/main/java/org/asynchttpclient/providers/grizzly/filters/AsyncHttpClientFilter.java

@@ -262,7 +262,7 @@ private boolean sendAsGrizzlyRequest(final RequestInfoHolder requestInfoHolder,
 
         if (Utils.requestHasEntityBody(request)) {
             final long contentLength = request.getContentLength();
-            if (contentLength > 0) {
+            if (contentLength >= 0) {
                 requestPacket.setContentLengthLong(contentLength);
                 requestPacket.setChunked(false);
             } else {