Add comment to QPDF_Name::writeJSON

libqpdf/QPDF_Name.cc

@@ -106,6 +106,8 @@ QPDF_Name::analyzeJSONEncoding(const std::string& name)
 void
 QPDF_Name::writeJSON(int json_version, JSON::Writer& p)
 {
+    // For performance reasons this code is duplicated in QPDF_Dictionary::writeJSON. When updating
+    // this method make sure QPDF_Dictionary is also update.
     if (json_version == 1) {
         p << "\"" << JSON::Writer::encode_string(normalizeName(name)) << "\"";
     } else {