private void logGotCredentialsFrom(String credentialSource) {
    logger.accept(LogEvent.lifecycle("Using " + credentialSource + " for " + imageReference));
  }
Creates a new {@link CredentialRetriever} that tries to retrieve credentials from <a
href="https://cloud.google.com/docs/authentication/production">Google Application Default
Credentials</a>.

@return a new {@link CredentialRetriever}
@see <a
    href="https://cloud.google.com/docs/authentication/production">https://cloud.google.com/docs/authentication/production</a>
jib-core/src/main/java/com/google/cloud/tools/jib/frontend/CredentialRetrieverFactory.java