toLowerCase

Changes the entire string to lower case.

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

and a record such as:

{
  "name" : "hEllO wORLd"
}

The following record path expression would remove extraneous whitespace:

RecordPath	Return value
trim(/message)	hello world