fix MyBusinessUnitDraft in generator mixin

Author: jenschude

api-java-mixin.raml

@@ -1389,7 +1389,7 @@ types:
   ScopedPrice:
     (java-extends): 'com.commercetools.api.models.Customizable<ScopedPrice>'
   MyBusinessUnitDraft:
-    (java-extends): 'com.commercetools.api.models.Customizable<MyBusinessUnitDraft>, com.commercetools.api.models.WithKey'
+    (java-extends): 'com.commercetools.api.models.CustomizableDraft<MyBusinessUnitDraft>, com.commercetools.api.models.WithKey'
   AssociateRolePagedQueryResponse:
     (java-extends): 'com.commercetools.api.models.ResourcePagedQueryResponse<AssociateRole>'
   AssociateRole: