code: public static BeanDescriptor getInstance(Class<?> type) {
          BeanDescriptor bd = cache.get(type);
          if (bd == null) {
              bd = new BeanDescriptor(type);
              BeanDescriptor existing = cache.putIfAbsent(type, bd);
              if (existing != null) {
                  bd = existing;
              }
          }
          return bd;
      }
docs: Gets an instance of ClassDescriptor for the specified class.
  
  @param type the class for which to lookup the method cache
  @return the method cache for the class