Why LinkedAccount#providerUserId is called like this while its content is a hashed password?

[bravegag]

Looking at the usage sample I am a bit puzzled on why the LinkedAccount#providerUserId is called like this while its content is a hashed password? Besides IMHO I don't think LinkedAccount requires a PK id it is superfluous as it is a Many-to-one user so it only needs the user_id as FK.