static <T> MapperFunction<T, T> of(Predicate<? super T> predicate) {
            requireNonNull(predicate, "predicate");

            return o -> {
                final boolean result = predicate.test(o);
                if (result) {
                    return o;
                } else {
                    return null;
                }
            };
        }
Creates a new {@link MapperFunction} from the specified {@link Predicate}.
core/src/main/java/com/linecorp/armeria/common/stream/FuseableStreamMessage.java