code: private static ConstructorMetadata loadMetadata(Class<?> clazz) {
      synchronized (clazz) {
        ConstructorMetadata metadata = cache.get(clazz);
        if (metadata == null) {
          ConstructorIntrospector introspector = new ConstructorIntrospector(clazz);
          introspector.process();
          metadata = introspector.metadataBuilder.build();
          cache.put(clazz, metadata);
        }
        return metadata;
      }
    }
docs: Loads the metadata, if it does not already exist in the cache.
  
  @param clazz
  the class to introspect
  @return the metadata