code: private GroovyClassLoader initGroovyLoader() {
          return (GroovyClassLoader) AccessController.doPrivileged(new PrivilegedAction() {
              public Object run() {
                  if (parentLoader instanceof GroovyClassLoader) {
                      return new ScriptClassLoader((GroovyClassLoader) parentLoader);
                  } else {
                      return new ScriptClassLoader(parentLoader, config);
                  }
              }
          });
      }
docs: Initialize a new GroovyClassLoader with a default or
  constructor-supplied parentClassLoader.
  
  @return the parent classloader used to load scripts