def config_types
      @config_types ||= begin
        config_types = {}
        
        registries = []
        each_registry do |ancestor, registry|
          registries.unshift(registry)
        end
        
        registries.each do |registry|
          registry.each_pair do |key, value|
            if value.nil?
              config_types.delete(key)
            else
              config_types[key] = value
            end
          end
        end
      
        config_types
      end
    end
def config_types
      @config_types ||= begin
        config_types = {}
        
        registries = []
        each_registry do |ancestor, registry|
          registries.unshift(registry)
        end
        
        registries.each do |registry|
          registry.each_pair do |key, value|
            if value.nil?
              config_types.delete(key)
            else
              config_types[key] = value
            end
          end
        end
      
        config_types
      end
    end
A hash of (key, ConfigType) pairs representing all config_types defined
 on this class or inherited from ancestors.  The config_types hash is
 memoized for performance.  Call reset_config_types if config_types needs
 to be recalculated for any reason.