I've have guessed that HttpUtils2 adds no header to it's requests - just as OSMDroid adds no header to it's tile requests.
In the b4a library source i have found the code that creates the tile requests and can see where i can simply add a line such as:
Code:
head.setHeader("User-Agent", "OSMDroid");
Following the thread on Google groups it's been said not to use 'OSMDroid' as a user-agent as technically speaking your application is not the official OSMDroid application.
I thought it'd be better to instead use the application packagename - but there's no way to get this packagename in the part of the code that sets the header.
And then we might find that using the packagename as the user-agent does not force the Mapnik tileserver to return tiles.
Or it might even be that the user-agent setting has no effect whatsoever on whether the Mapnik tileserver will return a tile - the Mapnik tileserver may only return a tile if it is not overloaded.
Martin.