/message/sendTransactionalWithEventDetails

Sends a previously prepared message as a transactional message including transaction details such as purchase confirmation,
and adds user as member to group the prepared message belong to .
Please be aware this may cause that user to be unexpectedly subscribed or re-subscribed to that group.

User can iterate through the list of items using for each expression to access the individual item.

User can specify any number of attributes aka transaction_details and access them using expression language.

It is strongly recommended to use the same structure for each item.

EXPLANATION
Var value refers to a single object inside the list of itemDetails, the name can by anything, in this case, it's the product.

Items value refers to eventDetails which is a placeholder for the list of items we want to show.
Max value is a limit of items to be displayed.
If you have max=50 but your JSON has less items, all of them will be displayed.
In the case of JSON with a number greater than the limit, the first 50 items will be shown and the rest will be ignored.
Inside ForEach, user can access itemDetails property using an array index with the name of the property user wants to access

Note that all query parameters are case-sensitive. Take a look at an example below:
- not "eventdetails" but "eventDetails"
- not "itemdetails " but "itemDetails"
"Request body example:

"

{
"parameters":
   [
       {"name" : "Parameter Name 1","value" : "Parameter Value 1"},
       {"name" : "Parameter Name 2","value": "Parameter Value 2"}
   ],
  "attachments": [
    {
      "name": "twitter_logo.png",
      "contentType": "image/png",
      "content": "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"
    }
  ],
"transaction": false   /(optional attribute)/
"eventDetailsProcessing":   /(optional attribute)/
   {
      "groupBy":"brandName",
      "groupLabel":"brandName",
      "valueField":"productName"
   },
"eventDetails":
   [
      {
          "itemDetails":[
                {"name":"productName","value":"Chair C1"},
                {"name":"brandName", "value":"aaa aaa"}
              ]
      },
      {
          "itemDetails":[
                {"name":"productName","value":"Sofa S1"},
                {"name":"brandName", "value":"bbb bbb"}
              ]
 
      },
      {
          "itemDetails":[
               {"name":"productName","value":"Bed B1"},
                {"name":"brandName", "value":"cccc cccc"}
              ]
 
      }
   ]
}