The Java code can be found in the Object folder within your project.
You can compile it with Eclipse using the B4A libraries (which are required). You can also edit the code from Java and recompile it to don Ecplipse or from the command line.
Clients should not complain about using external libraries (BA4) because Java developers use them and buy different ones.
In fact, by purchasing B4A, you purchase the IDE that translates the B4A code into Java, but also the libraries of the AnyWhere Software and the rights to use them. (Obviously you can not distribute the Libraries, but they have to get them too)