private and non-final fields in Java 9 interfaces

[Ess Kay]

(This is not a jigsaw specific specific question but I could not find
a more appropriate mailing list. The COIN list is archived.  If there
is a a more appropriate mailing list then please let me know.)

The Java 9 compiler currently allows
1) private static and instance fields and
2) non-final static and instance fields.
Is this a bug?  If not then are these changes specified or mentioned anywhere?