opnsense-src/test/Modules/Inputs/preprocess/module.modulemap

module fwd { header "fwd.h" export * }
module file { header "file.h" header "file2.h" header "other.h" export * }
module nested {
  module a { header "a.h" }
  module b { header "b.h" }
  module c { header "c.h" }
}