public CredentialRetriever dockerConfig(Path dockerConfigFile) {
    return dockerConfig(
        DockerConfigCredentialRetriever.create(imageReference.getRegistry(), dockerConfigFile));
  }
Creates a new {@link CredentialRetriever} that tries to retrieve credentials from a custom path
to a Docker config.

@param dockerConfigFile the path to the Docker config file
@return a new {@link CredentialRetriever}
@see DockerConfigCredentialRetriever
jib-core/src/main/java/com/google/cloud/tools/jib/frontend/CredentialRetrieverFactory.java