MySQL 5.7 do not allow PK values defaults to NULL which fails the
migration step and the following message is prompted.
'All parts of a PRIMARY KEY must be NOT NULL;
if you need NULL in a key, use UNIQUE instead'
Also refer to #1567899 for more detail.
Change-Id: Ia16405cd593a0a67e7c7ae68a3977b74cc673d0b