public Optional<ContainerConfigurationTemplate> retrieveLocalConfig(DescriptorDigest imageId)
      throws IOException {
    return cacheStorageReader.retrieveLocalConfig(imageId);
  }
Retrieves the {@link ContainerConfigurationTemplate} for the image saved from the given image
ID. An image ID is a SHA hash of a container configuration JSON. The value is also shown as
IMAGE ID in {@code docker images}.

<p>Note: the {@code imageId} is only used to find the {@code containerConfiguration}, and is
not necessarily the actual SHA of {@code containerConfiguration}. There is no guarantee that
{@code containerConfiguration}'s SHA will be {@code imageId}, since the saved container
configuration is not a direct copy of the base image's original configuration.

@param imageId the image ID
@return the {@link ContainerConfigurationTemplate} referenced by the image ID, if found
@throws IOException if an I/O exception occurs
jib-core/src/main/java/com/google/cloud/tools/jib/cache/Cache.java