update package s2ioperator

Signed-off-by: soulseen <sunzhu@yunify.com>

vendor/github.com/go-openapi/spec/schema.go

@@ -163,7 +163,6 @@ type SchemaProps struct {
 	Schema               SchemaURL         `json:"-"`
 	Description          string            `json:"description,omitempty"`
 	Type                 StringOrArray     `json:"type,omitempty"`
-	Nullable             bool              `json:"nullable,omitempty"`
 	Format               string            `json:"format,omitempty"`
 	Title                string            `json:"title,omitempty"`
 	Default              interface{}       `json:"default,omitempty"`
@@ -303,12 +302,6 @@ func (s *Schema) AddType(tpe, format string) *Schema {
 	return s
 }
 
-// AsNullable flags this schema as nullable.
-func (s *Schema) AsNullable() *Schema {
-	s.Nullable = true
-	return s
-}
-
 // CollectionOf a fluent builder method for an array parameter
 func (s *Schema) CollectionOf(items Schema) *Schema {
 	s.Type = []string{jsonArray}