_computeHash(hashFunction) {
        const hash = webpack.util.createHash(hashFunction);

        hash.update(this.content);

        if (this.layer) {
          hash.update(this.layer);
        }

        hash.update(this.supports || "");
        hash.update(this.media || "");
        hash.update(this.sourceMap || "");

        return hash.digest("hex");
      }
@private
@param {string} hashFunction
@returns {string | Buffer}