public CredentialRetriever dockerCredentialHelper(String credentialHelper) {
    return dockerCredentialHelper(Paths.get(credentialHelper));
  }
Creates a new {@link CredentialRetriever} for retrieving credentials via a Docker credential
helper, such as {@code docker-credential-gcr}.

@param credentialHelper the credential helper executable
@return a new {@link CredentialRetriever}
jib-core/src/main/java/com/google/cloud/tools/jib/frontend/CredentialRetrieverFactory.java