@Nullable
  private DelegatingScript loadScriptFromSystemPropertyInducedLocation(String propertyKey) {
    String location = System.getProperty(propertyKey);
    if (location == null || location.length() == 0) return null;

    DelegatingScript script = loadScriptFromClassPathLocation(location);
    if (script != null) return script;

    script = loadScriptFromFileSystemLocation(location);
    if (script != null) return script;

    throw new ConfigurationException("Cannot find configuration script '%s'", location);
  }
For testing purposes. Do not use directly.
spock-core/src/main/java/org/spockframework/runtime/ConfigurationScriptLoader.java