In particular, do not use com.sun.javadoc deprecated since Java 9 and
finally removed in Java 13, to allow the tests to run under modern JRE.
They don't run under Java 8 and earlier any more, but this shouldn't be
a huge problem nowadays and as SWIG output is independent from the Java
version used, it's enough to test it with modern Java versions.
Note that the tests themselves were changed only in the most minimal
way, to adapt them to the new way of running javadoc (which is now also
integrated into CommentParser itself instead of being duplicated in
every test).
This is done mainly to avoid problems with trailing whitespace in the
generated Python code as this provokes pep8 problems, but is also, arguably,
more logical, as if a command which is on its own on a line is ignored, we
shouldn't leave any whitespace neither (and perhaps should even suppress the
line entirely, in fact).
Add %feature("doxygen:ignore:<command>") implementation, documentation and
test case.
This feature allows to use custom tags in C++ Doxygen comments for
C++-specific things that don't make sense in the context of the target
language and also allows to insert contents specific to the target language in
the C++ comments using (different) custom commands, which is very useful in
practice to explain the particularities of the API wrappers.