Incorporating review comments

Signed-off-by: Matthias Hanel <mh@synadia.com>

server/accounts.go

@@ -2849,7 +2849,7 @@ func (s *Server) updateAccountClaimsWithRefresh(a *Account, ac *jwt.AccountClaim
 	// update account signing keys
 	a.signingKeys = nil
 	if len(ac.SigningKeys) > 0 {
-		a.signingKeys = map[string]jwt.Scope{}
+		a.signingKeys = make(map[string]jwt.Scope, len(ac.SigningKeys))
 	}
 	signersChanged := false
 	for k, scope := range ac.SigningKeys {
@@ -3157,7 +3157,7 @@ func (s *Server) updateAccountClaimsWithRefresh(a *Account, ac *jwt.AccountClaim
 			c.mu.Lock()
 			sk := c.user.SigningKey
 			c.mu.Unlock()
-			if sk == "" {
+			if sk == _EMPTY_ {
 				continue
 			}
 			if _, ok := alteredScope[sk]; ok {

server/auth.go

@@ -561,7 +561,7 @@ func (s *Server) processClientOrLeafAuthentication(c *client, opts *Options) boo
 			return false
 		}
 		// this only executes IF there's an issuer on the Juc - otherwise the account is already vetted
-		if juc.IssuerAccount != "" {
+		if juc.IssuerAccount != _EMPTY_ {
 			if scope, ok := acc.hasIssuer(juc.Issuer); !ok {
 				c.Debugf("User JWT issuer is not known")
 				return false

server/client.go

@@ -688,7 +688,7 @@ func (c *client) applyAccountLimits() {
 		if uc, _ := jwt.DecodeUserClaims(c.opts.JWT); uc != nil {
 			c.mpay = int32(uc.Limits.Payload)
 			c.msubs = int32(uc.Limits.Subs)
-			if uc.IssuerAccount != "" && uc.IssuerAccount != uc.Issuer {
+			if uc.IssuerAccount != _EMPTY_ && uc.IssuerAccount != uc.Issuer {
 				if scope, ok := c.acc.signingKeys[uc.Issuer]; ok {
 					if userScope, ok := scope.(*jwt.UserScope); ok {
 						// if signing key disappeared or changed and we don't get here, the client will be disconnected

server/jwt_test.go

@@ -4571,7 +4571,7 @@ func newUserEx(t *testing.T, accKp nkeys.KeyPair, scoped bool, issuerAccount str
 	uclaim := newJWTTestUserClaims()
 	uclaim.Subject = upub
 	uclaim.SetScoped(scoped)
-	if issuerAccount != "" {
+	if issuerAccount != _EMPTY_ {
 		uclaim.IssuerAccount = issuerAccount
 	}
 	ujwt, err := uclaim.Encode(accKp)