constructor(
    opts: $ReadOnly<{
      dependencyExtractor: ?string,
      enableHastePackages: boolean,
      enableWorkerThreads: boolean,
      hasteImplModulePath: ?string,
      maxFilesPerWorker?: ?number,
      maxWorkers: number,
      perfLogger: ?PerfLogger,
    }>,
  ) {
    this.#dependencyExtractor = opts.dependencyExtractor;
    this.#enableHastePackages = opts.enableHastePackages;
    this.#enableWorkerThreads = opts.enableWorkerThreads;
    this.#hasteImplModulePath = opts.hasteImplModulePath;
    this.#maxFilesPerWorker = opts.maxFilesPerWorker ?? MAX_FILES_PER_WORKER;
    this.#maxWorkers = opts.maxWorkers;
    this.#perfLogger = opts.perfLogger;
  }
Only if processing has already required reading the file's contents, return
the contents as a Buffer - null otherwise. Not supported for batches.