fixup for older go

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util.go

@@ -92,10 +92,15 @@ func newPathRequest(path string, method string, body string, msg interface{}, ta
 			continue
 		}
 		fld := tmsg.Type().Field(i)
+		// Skip unexported fields.
+		if fld.PkgPath != "" {
+			continue
+		}
+		/* check for empty PkgPath can be replaced with new method IsExported
 		if !fld.IsExported() {
 			continue
 		}
-
+		*/
 		t := &tag{}
 		for _, tn := range tags {
 			ts, ok := fld.Tag.Lookup(tn)