code: private boolean isParentFirst(String resourceName) {
          // default to the global setting and then see
          // if this class belongs to a package which has been
          // designated to use a specific loader first
          // (this one or the parent one)
  
          // TODO shouldn't this always return false in isolated mode?
  
          boolean useParentFirst = parentFirst;
  
          for (Enumeration e = systemPackages.elements(); e.hasMoreElements();) {
              String packageName = (String) e.nextElement();
              if (resourceName.startsWith(packageName)) {
                  useParentFirst = true;
                  break;
              }
          }
          for (Enumeration e = loaderPackages.elements(); e.hasMoreElements();) {
              String packageName = (String) e.nextElement();
              if (resourceName.startsWith(packageName)) {
                  useParentFirst = false;
                  break;
              }
          }
          return useParentFirst;
      }
docs: Tests whether or not the parent classloader should be checked for a
  resource before this one. If the resource matches both the "use parent
  classloader first" and the "use this classloader first" lists, the latter
  takes priority.
  
  @param resourceName
  The name of the resource to check. Must not be
  <code>null</code>.
  
  @return whether or not the parent classloader should be checked for a
  resource before this one is.