introduce a logging.CloseReason for version negotiation errors

logging/close_reason.go

@@ -13,6 +13,7 @@ type CloseReason struct {
 
 	timeout             *TimeoutReason
 	statelessResetToken *StatelessResetToken
+	versions            []VersionNumber
 }
 
 // NewApplicationCloseReason creates a new CloseReason for an application error.
@@ -35,6 +36,11 @@ func NewStatelessResetCloseReason(token StatelessResetToken) CloseReason {
 	return CloseReason{statelessResetToken: &token}
 }
 
+// NewVersionNegotiationError creates a new CloseReason for a version negotiation error.
+func NewVersionNegotiationError(versions []VersionNumber) CloseReason {
+	return CloseReason{versions: versions}
+}
+
 // ApplicationError gets the application error.
 func (r *CloseReason) ApplicationError() (errorCode ApplicationError, remote bool, ok bool) {
 	if r.applicationError == nil {
@@ -66,3 +72,7 @@ func (r *CloseReason) StatelessReset() (token StatelessResetToken, ok bool) {
 	}
 	return *r.statelessResetToken, true
 }
+
+func (r *CloseReason) VersionNegotiation() (versions []VersionNumber, ok bool) {
+	return r.versions, len(r.versions) > 0
+}