static BooleanType booleanType() {
        return new BooleanType();
    }
When used in the context of a condition, the condition can only match if the
value was truthful. This means that a certain expression can be a different
type, for example, {@code OptionalType<T>} will become {@code T}.

@return The type, given that it has been proven truthy
smithy-rules-engine/src/main/java/software/amazon/smithy/rulesengine/language/evaluation/type/Type.java