docs: private RegistryAuthSupplier googleContainerRegistryAuthSupplier() throws MojoExecutionException {
      GoogleCredentials credentials = null;
  
      final String googleCredentialsPath = System.getenv("DOCKER_GOOGLE_CREDENTIALS");
      if (googleCredentialsPath != null) {
        final File file = new File(googleCredentialsPath);
        if (file.exists()) {
          try {
            try (FileInputStream inputStream = new FileInputStream(file)) {
              credentials = GoogleCredentials.fromStream(inputStream);
              getLog().info("Using Google credentials from file: " + file.getAbsolutePath());
            }
          } catch (IOException ex) {
            throw new MojoExecutionException("Cannot load credentials referenced by "
                                             + "DOCKER_GOOGLE_CREDENTIALS environment variable", ex);
          }
        }
      }
  
      // use the ADC last
      if (credentials == null) {
        try {
          credentials = GoogleCredentials.getApplicationDefault();
          getLog().info("Using Google application default credentials");
        } catch (IOException ex) {
          // No GCP default credentials available
          getLog().debug("Failed to load Google application default credentials", ex);
        }
      }
  
      if (credentials == null) {
        return null;
      }
  
      return ContainerRegistryAuthSupplier.forCredentials(credentials).build();
    }