@Override
  public void close() {
    Preconditions.checkNotNull(progressEventDispatcher);
    Preconditions.checkNotNull(throttledDispatcher);
    throttledDispatcher.close();
    progressEventDispatcher.close();
  }
Contains a {@link ProgressEventDispatcher} and throttles dispatching progress events with the
default delay used by {@link ThrottledAccumulatingConsumer}. This class is mutable and should
only be used within a local context.

<p>This class is necessary because the total BLOb size (allocation units) is not known until the
response headers are received, only after which can the {@link ProgressEventDispatcher} be
created.
jib-core/src/main/java/com/google/cloud/tools/jib/builder/steps/ThrottledProgressEventDispatcherWrapper.java