import com.google.common.base.Function; import com.google.common.base.Optional; class A { public Optional<String> transform(Optional<Integer> p<caret>1) { return p1.transform(new MyFunction()); } class MyFunction implements Function<Integer, String> { @Override public String apply(Integer input) { return null; } public String apply2(Integer input) { return null; } @Override public boolean equals(Object object) { return false; } } }