import java.util.Collections; import java.util.List; class A {} class B { B(List> list) {} } class Bug { private static B case1(A a) { return new B(Collections.singletonList(a)); } private static B case2(A a) { return new B(Collections.singletonList(a)); } public static void main(String[] args) { System.out.println(case1(new A())); System.out.println(case2(new A())); } }