$ javac src/WithDefault.java && java WithDefault     (21.0.10+7-Ubuntu-124.04)
fee for Wallet(1000) = 15   (the rule for Wallet is 1 percent, so 10; it compiled without any complaint)

$ javac src/WithDefault.java && java WithDefault     (25.0.4.1+1-LTS)
fee for Wallet(1000) = 15   (the rule for Wallet is 1 percent, so 10; it compiled without any complaint)

$ javac src/WithDefault.java && java WithDefault     (27+35)
fee for Wallet(1000) = 15   (the rule for Wallet is 1 percent, so 10; it compiled without any complaint)