public Terrain getTerrainAtCell(Vector3f cellCoordinate) {
        return cache.get(cellCoordinate);
    }
Get the terrain tile at the specified XZ cell coordinate (not world coordinate).
@param cellCoordinate integer cell coordinates
@return the terrain tile at that location
jme3-terrain/src/main/java/com/jme3/terrain/geomipmap/TerrainGrid.java