HyperNext Developer is a visual tool that creates plugins for HAC. It is currently undergoing testing.
Developer can only create plugings using the HyperNext language and not Jave, C++ etc.
As HAC comes from HyperNext Studio and has many similarities you might also find help on Developer and Plugins in the HyperNext Studio forums.
http://www.tigabyte.com/forums/viewforum.php?f=10Note, If your questions are Android related then please post them in these Android forums and not the HyperNext Studio forums.