public static OptionalLong ofNullable(Long l) {
        if (l == null) {
            return OptionalLong.empty();
        } else {
            return OptionalLong.of(l);
        }
    }
Wraps the specified nullable value in an {@code OptionalLong}.

@param l  the value
@return   the wrapped optional
runtime-parent/runtime-core/src/main/java/com/speedment/runtime/core/util/OptionalUtil.java