* @param language the language of the sources to return, or {@code null} for all languages
     */
    @Nonnull
    Stream<SourceRoot> getEnabledSourceRoots(
            @Nonnull Project project, @Nullable ProjectScope scope, @Nullable Language language);

    /**
     * Adds the given source to the given project.

        return prj.getSourceRoots();
    }

    @Nonnull
    @Override
    public Stream<SourceRoot> getEnabledSourceRoots(@Nonnull Project project, ProjectScope scope, Language language) {
        MavenProject prj = getMavenProject(requireNonNull(project, "project" + " cannot be null"));
        return prj.getEnabledSourceRoots(scope, language);
    }

    @Override