Allow the NIC VLAN to be set to an empty string

The NIC VLAN has previously not been modified via Haskell, causing the
INicParams class not to be used. With the recent job queue
refactorings, a modification definition is recorded, and for an empty
string (which is a legal default value) a crash happens. This patch
fixes this by allowing VLANS to be empty strings on the Haskell side.
Signed-off-by: Hrvoje Ribicic <riba@google.com>
Reviewed-by: Thomas Thrainer <thomasth@google.com>

src/Ganeti/OpParams.hs

@@ -337,7 +337,7 @@ $(buildObject "INicParams" "inic"
   , optionalField $ simpleField C.inicMode   [t| NonEmptyString |]
   , optionalField $ simpleField C.inicLink   [t| NonEmptyString |]
   , optionalField $ simpleField C.inicName   [t| NonEmptyString |]
-  , optionalField $ simpleField C.inicVlan   [t| NonEmptyString |]
+  , optionalField $ simpleField C.inicVlan   [t| String         |]
   , optionalField $ simpleField C.inicBridge [t| NonEmptyString |]
   ])
 

test/hs/Test/Ganeti/OpCodes.hs

@@ -88,7 +88,7 @@ instance Arbitrary OpCodes.DiskIndex where
 instance Arbitrary INicParams where
   arbitrary = INicParams <$> genMaybe genNameNE <*> genMaybe genName <*>
               genMaybe genNameNE <*> genMaybe genNameNE <*>
-              genMaybe genNameNE <*> genMaybe genNameNE <*>
+              genMaybe genNameNE <*> genMaybe genName <*>
               genMaybe genNameNE
 
 instance Arbitrary IDiskParams where