code: static SpanExporterImpl create(int bufferSize, Duration scheduleDelay) {
      // TODO(bdrutu): Consider to add a shutdown hook to not avoid dropping data.
      Worker worker = new Worker(bufferSize, scheduleDelay);
      return new SpanExporterImpl(worker);
    }
docs: Constructs a {@code SpanExporterImpl} that exports the {@link SpanData} asynchronously.
  
  <p>Starts a separate thread that wakes up every {@code scheduleDelay} and exports any available
  spans data. If the number of buffered SpanData objects is greater than {@code bufferSize} then
  the thread wakes up sooner.
  
  @param bufferSize the size of the buffered span data.
  @param scheduleDelay the maximum delay.