isEmpty

Apache NiFi RecordPath Guide

Also available as:

Returns true if the provided value is either null or is an empty string.

RecordPath	Return value
`/name[isEmpty(/details/employer)]`	John Doe
`/name[isEmpty(/details/vehicle)]`	John Doe
`/name[isEmpty(/details/phase)]`	<returns no results>
`/name[isEmpty(.)]`	<returns no results>