Class diagrams
The class diagrams in API Extended Document were made using Visual Paradigm. This is a paid software, however you can have a free-trial for 30 days.
You have to know, when exporting diagrams, because it is a free trial, some parasitic text appears:
For removing them, we export diagrams in an SVG format, it allows us to modify the diagram very easily. To remove parasites, open the SVG file with a text editor (Atom, etc.). Go to the bottom of the file, and remove everything similar to what is underlined in this image.
You have then a clean SVG file, if you want to be able to visualize it on github you need to convert the SVG to a new png file. It can be done using an svg to png converter, many are available on the Internet.
We then get this:
