presto-spi/src/main/java/io/prestosql/spi/predicate/Primitives.java/Primitives/add
class Primitives:    private static void add(Map<Class<?>, Class<?>> forward,
            Map<Class<?>, Class<?>> backward, Class<?> key, Class<?> value)
    {
        forward.put(key, value);
        backward.put(value, key);
    }