Append String Transformer Reference
+ *Purpose:* Appends a string to a string payload.
Minimum Configuration: The string to append to the message payload.
Discussion: The Append String Transformer has the same advanced properties as all other transformers. Configuring these optional properties is covered in the [Studio Transformers] page.
You must specify the string that the transformer appends to the message payload. Click the General tab and place the string in the Message field.
Use the Advanced tab to optionally configure the properties standard to all transformers.
Mule ESB Reference
For more information, see here.