I'm creating the jdbc UserConnection table that is defined in the spring social JdbcUserConnectionRepository.sql and I noticed that providerUserId column isn't created as 'not null'...

create table UserConnection (userId varchar(255) not null,
providerId varchar(255) not null,
providerUserId varchar(255),
rank int not null,
displayName varchar(255),......


Is it possible the providerUserId could be null in this table? I was going to make it not null in our Oracle DB but wasn't sure of the implications of doing so?

TIA