rpm upstream dropped support of language specific provides/requires generators.
The idea is that they get moved to the specific language packages. This has
already happened for languages like perl/python/ruby, but not for mono.

rpm currently comes with three files for mono dependency generation:

/usr/lib/rpm/fileattrs/mono.attr
/usr/lib/rpm/mono-find-provides
/usr/lib/rpm/mono-find-requires

This files need to be moved to the mono-devel packages.

Note that mono-devel already has /usr/bin/mono-find-provies and
/usr/bin/mono-find-requires. They are a bit different to the ones in the rpm
package, so some changes may need to be merged.

The mono.attr file currently looks like this:
%__mono_provides        %{_rpmconfigdir}/mono-find-provides
%{_builddir}/%{?buildsubdir} %{buildroot} %{_libdir}
%__mono_requires        %{_rpmconfigdir}/mono-find-requires
%{_builddir}/%{?buildsubdir} %{buildroot} %{_libdir}
%__mono_magic           Mono/.Net assembly

You may want to usr %{_bindir} instead if %{_rpmconfigdir} if you want to use
the scripts in /usr/bin.