CREATE TABLE table_name_15 (name VARCHAR(255), moving_from VARCHAR(255), transfer_window VARCHAR(255), transfer_fee VARCHAR(255))
What is the name of the player with a transfer window in summer, an undisclosed transfer fee, and is moving from brussels?
    
SQL: SELECT name FROM table_name_15 WHERE transfer_window = "summer" AND transfer_fee = "undisclosed" AND moving_from = "brussels"