It is not possible to disable foreign key generation for the following mappings:

@PKJC 
OneToOne(optional = false)
@JoinColumn(foreignKey=@ForeignKey(NO_CONSTRAINT))
private Parent parent;

and

@OneToOne 
@MapsId 
@JoinColumn(name="FK", foreignKey=@ForeignKey(NO_CONSTRAINT))

The second mapping is probably related to HHH-12320 Open .

There was also a comment added to HHH-11180 Closed after it was closed that is related.