Hi Jun,
The team that creates the SDKs has changed the way they include the SDK files over time. In the version you have, they were included as a link. In SDKs which were produced some time later than this one, they realized it was better to include them directly into the project by copying them. I'm not aware of any automated way to change this for the version you have, but probably you could copy the files in and remove the links. The issue is that you probably would not be able to use the SDK management tools to detach this SDK in the future. For the newer SDKs which are copied, the SDK management tools are setup to add/remove SDK files when attach or detach operations are peformed.
Best Regards,
Mike