This may fall in the truth and beauty column, but it seems to me that for PrivateCredentialPermission, a.equals(b) should be true if and only if a.implies(b) and b.implies(a) are both true. (This seems to me like the right generic definition of Permission.equals.) Currently, two instances that differ merely in the order of principals, such as targets
    baz foo \"foo\" bar \"bar"
and
    baz bar \"bar\" foo \"foo\"
and not considered equal (according to the equals method), nor do they hash the same, even though they imply each other.