3.15Conditional fields

This is different and extremely useful.

Suppose:

{
  "name": "Acme",
  "phone": null
}

You don't want to send:

{
  "Phone": null
}

at all.

You can conditionally include a field:

{
    Name: payload.name,
    (Phone: payload.phone) if (payload.phone != null)
}

So if phone exists:

{
  "Name": "Acme",
  "Phone": "305-555-1234"
}

If it doesn't:

{
  "Name": "Acme"
}

This is an excellent Mule/Salesforce interview example because it demonstrates that you understand patch/update semantics, not only syntax.