# File lib/active_record/connection_adapters/jdbc_adapter.rb, line 452
      def initialize(connection, logger, config)
        @config = config
        spec = adapter_spec config
        unless connection
          connection_class = jdbc_connection_class spec
          connection = connection_class.new config
        end
        super(connection, logger)
        extend spec if spec
        connection.adapter = self
        JndiConnectionPoolCallbacks.prepare(self, connection)
      end