suggested method to create LibreOffice Extensions

Hello everyone,
almost three years ago I received help from this mailing list to create 
an extension for LibreOffice, which became "FirmaconDike" (thanks!):
http://extensions.libreoffice.org/extension-center/firmacondike-1

Today I have to re-examine this issue in a LibreOffice lesson, in witch 
I would like to explain how to create an extension "from scratch".

I thought to write a simple macro with students, such as "Hello world", 
and explain step by step how to generate the oxt file.

Seeking documentation, I saw a lot of confusion on the subject and the 
argument (as you know) is only present on the site of AOO.

I tried to use BAB Paolo Mantovani, both in the new version that in the 
previous one, and it seemed a very good macro to create extensions.

The Extension oxt who created BAB does not work, then I fear that BAB is 
incompatible with LibreOffice (I have the 5.0.2.2). Opening it, it gives 
me an error:
(Com.sun.star.deployment.DeploymentException) {{Message = "You \ X00e8 
an error occurred while enabling: HelloWorld" Context = 
(com.sun.star.uno.XInterface) @ 7f2fec3ef8b0}, Cause = ( any) 
{(com.sun.star.lang.IllegalArgumentException) {{{Message = "" Context = 
(com.sun.star.uno.XInterface) @ 0}}, ArgumentPosition = (short) 0}}}

Here you can find the extension generated by BAB:
http://www.libreitalia.it/cloud/public.php?service=files&t=77d91958fb91ecab19ec2b0b62844d63

I have not tried a "reverse engineering" of oxt file to understand what 
it changes from another oxt  (such as "FirmaconDike"), looking for 
suggestions from you, who are much more experienced than me.

Does anyone have experience with BAB and LibreOffice?
What is the official method (or recommended one) to create extensions 
for LibreOffice?

I apologize if you have already solved this problem in another thread

Thank you,

Andrea Castellani
www.libreitalia.it