class TestData<K> {} interface TerminalOp<L, M> extends IntermediateOp<L, M> {} interface IntermediateOp<L1, M1> { boolean m(L1 l, M1 m);} class Test<T, U> { protected U exerciseOps(TestData<T> data, TerminalOp<T, U> terminal, IntermediateOp<T, U>... ops) { return exerciseOps(data, terminal, (u, v) -> u.equals(v)); } } class Test1 { protected <T, U> U exerciseOps(TestData<T> data, TerminalOp<T, U> terminal, IntermediateOp... ops) { return exerciseOps(data, terminal, (u, v) -> u.equals(v)); } } class Test2 { protected <T, U> U exerciseOps(TestData<T> data, TerminalOp<T, U> terminal, IntermediateOp<T, U>... ops) { return exerciseOps(data, terminal, (u, v) -> u.equals(v)); } }