in lib/plugin.js [213:222]
beforeHtmlGeneration(compilation) {
const itemsBySprite = this.map.groupItemsBySpriteFilename();
const sprites = Object.keys(itemsBySprite).reduce((acc, filename) => {
acc[this.filenamePrefix + filename] = compilation.assets[this.filenamePrefix + filename].source();
return acc;
}, {});
return sprites;
}