public static Path getConfigDir() {
    String configDirProperty = System.getProperty(PropertyNames.CONFIG_DIRECTORY);
    if (!Strings.isNullOrEmpty(configDirProperty)) {
      return Paths.get(configDirProperty);
    }
    return XdgDirectories.getConfigHome();
  }
Returns the config directory set by {@link PropertyNames#CONFIG_DIRECTORY} if not null,
otherwise returns the default config directory.

@return the config directory set by {@link PropertyNames#CONFIG_DIRECTORY} if not null,
    otherwise returns the default config directory.
jib-plugins-common/src/main/java/com/google/cloud/tools/jib/plugins/common/globalconfig/GlobalConfig.java