docs: private TileBitmap createBackgroundBitmap(RenderContext renderContext) {
          TileBitmap bitmap = this.graphicFactory.createTileBitmap(renderContext.rendererJob.tile.tileSize, renderContext.rendererJob.hasAlpha);
          renderContext.canvasRasterer.setCanvasBitmap(bitmap);
          if (!renderContext.rendererJob.hasAlpha) {
              renderContext.canvasRasterer.fill(renderContext.renderTheme.getMapBackgroundOutside());
          }
          return bitmap;
  
      }