camel-salesforce - Lookups to polymorphic relationship fields must include an attributes object with a type property

When referencing a related record that is a polymorphic lookup, the JSON must include an attributes object with a type property indicating which type of Object is being referenced.

E.g.:

{
  "Description": "Contact HR for further information",
  "Status": "Completed",
  "Who": {
    "attributes": {
      "type": "Contact"
    },
    "External_Id_Field__c": "cfcec54d-5d77-4ffa-a2ec-7fa2ce0e9616"
  },
  "Subject": "Comment"
}

This attributes object is optional for non-polymorphic lookups, so no harm in including it in all lookups.