public Optional<ManifestAndDigest<ManifestTemplate>> checkManifest(String imageQualifier)
      throws IOException, RegistryException {
    ManifestChecker<ManifestTemplate> manifestChecker =
        new ManifestChecker<>(
            registryEndpointRequestProperties, imageQualifier, ManifestTemplate.class);
    return callRegistryEndpoint(manifestChecker);
  }
Check if a manifest referred to by {@code imageQualifier} (tag or digest) exists on the
registry.

@param imageQualifier the tag or digest to check for
@return the {@link ManifestAndDigest} referred to by {@code imageQualifier} if the manifest
    exists on the registry, or {@link Optional#empty()} otherwise
@throws IOException if communicating with the endpoint fails
@throws RegistryException if communicating with the endpoint fails
jib-core/src/main/java/com/google/cloud/tools/jib/registry/RegistryClient.java