There are a few tests that offsets have been initialized in javaClasses, e.g:

bool java_lang_ClassLoader::parallelCapable(oop class_loader) {
  if (parallelCapable_offset == -1) {
     // Default for backward compatibility is false
     return false;
  }
   return (class_loader->obj_field(parallelCapable_offset) != NULL);
}

Assumedly these are backwards compatibility precautions relevant in the era of hsx. All cases can now be removed or turned into assertions.