THEME: Contour lines not visible

[moiatto]

I downloaded the default.xml theme, saved in assets folder and called:

// Render theme
AssetsRenderTheme assetsRenderTheme = new AssetsRenderTheme(requireContext().getAssets(), "", THEME_DEFAULT);
theme = map.setTheme(assetsRenderTheme);

until here it's ok.

Now, for test, I edited the default.xml theme, adding the contour lines (found as an answer in a post):

<!-- contour lines -->
<m e="way" k="contour_ext">
    <m v="elevation_minor">
        <m zoom-max="13" zoom-min="13">
            <line stroke="#641616" width="0.4" />
        </m>
    </m>
    <m v="elevation_medium|elevation_major">
        <m zoom-max="13" zoom-min="13">
            <line stroke="#630a0c" width="0.6" />
        </m>
    </m>
</m>

No contour lines drawed...

Where can be the problem? wrong key "contour_ext" ? wrong values "elevation_minor"?

I use mapsforge map V5.