docs: @Override
     public <R1> R1 collect(Supplier<R1> supplier, BiConsumer<R1, ? super R> accumulator, BiConsumer<R1, R1> combiner) {
        return performOperation(TerminalFunctions.collectFunction(supplier, accumulator, combiner), true,
                (e1, e2) -> {
                   combiner.accept(e1, e2);
                   return e1;
                }, null);
     }