rpc/api allow empty password

rpc/api/personal_args.go

@@ -46,7 +46,7 @@ func (args *NewAccountArgs) UnmarshalJSON(b []byte) (err error) {
 
 type UnlockAccountArgs struct {
 	Address    string
-	Passphrase string
+	Passphrase *string
 	Duration   int
 }
 
@@ -70,7 +70,7 @@ func (args *UnlockAccountArgs) UnmarshalJSON(b []byte) (err error) {
 
 	if len(obj) >= 2 && obj[1] != nil {
 		if passphrasestr, ok := obj[1].(string); ok {
-			args.Passphrase = passphrasestr
+			args.Passphrase = &passphrasestr
 		} else {
 			return shared.NewInvalidTypeError("passphrase", "not a string")
 		}