public void resetCachedNeighbours() {
        if (children != null) {
            for (int x = children.size(); --x >= 0;) {
                Spatial child = children.get(x);
                if (child instanceof TerrainQuad) {
                    ((TerrainQuad) child).resetCachedNeighbours();
                } else if (child instanceof TerrainPatch) {
                    TerrainPatch patch = (TerrainPatch) child;
                    patch.searchedForNeighboursAlready = false;
                }
            }
        }
    }
Reset the cached references of neighbours.
TerrainQuad caches neighbours for faster LOD checks.
Sometimes you might want to reset this cache (for instance in TerrainGrid)
jme3-terrain/src/main/java/com/jme3/terrain/geomipmap/TerrainQuad.java