Document that `BearerToken.ToV2` method return `nil`
when called on `nil`. Write corresponding unit tests.
Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
With new neofs-api changes, token issuer will not be stored
in ownerID field of bearer token. We can identify owner by
public key that has been used in signature.
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
Now owner ID field is not required to be set. According to
latest neofs-api, this field set if token was issued for
specific owner ID. If this field is not set, then any user
can use this token while it is correctly signed and has valid
lifetime.
Lifetime is also can be omitted since node interpret empty
lifetime as a lifetime with zero values.
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
