toUpperCase

Change the entire String to upper case

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

and a record such as:

{
  "fullName" : "john smith"
}

The following record path expression would remove extraneous whitespace:

RecordPath	Return value
toUpperCase(/name)	JOHN SMITH