Service-side stitching JSON data format correctly (Append way)

We usually in the service side mosaic JSON data returned to the client, the first kind of appendformat way stitching, this method is not, the correct stitching way is append way

We usually send JSON data back to the client at the service end, sometimes we will use the first AppendFormat stitching, this method is not valid, the JSON contains the symbol "{", and the concatenation of the symbols of the placeholder conflict {0}--"{", the report entered a string format is not correct.
So our correct stitching is the append way.