padLeft

Prepends characters to the input String until it reaches the desired length.

{
  "type": "record",
  "name": "events",
  "fields": [
    { "name": "name", "type": "string" }
  ]
}

and a record such as:

{
  "name" : "john smith"
}

The following record path expression would prepend '@' characters to the input String:

RecordPath	Return value
padLeft(/name, 15, '@')	@@@@@john smith