docs: function createContentsZip(pluginDir, manifest) {
    return new Promise((res, rej) => {
      const output = new streamBuffers.WritableStreamBuffer();
      const zipFile = new ZipFile();
      let size = null;
      output.on("finish", () => {
        debug(`plugin.zip: ${size} bytes`);
        res(output.getContents());
      });
      zipFile.outputStream.pipe(output);
      sourceList(manifest).forEach(src => {
        zipFile.addFile(path.join(pluginDir, src), src);
      });
      zipFile.end(finalSize => {
        size = finalSize;
      });
    });
  }