* feat: Login Rule support for email.local and regexp.replace
This commit updates the `stringListMap` function to filter out values
that map to the empty string.
This is used by `email.local` and `regexp.replace` only.
The empty values were already being filtered out in
`(*TraitsTemplateExpression).Interpolate`, adding the filtering here
just makes it more convenient to call these functions in the Login Rule
parser in teleport.e where it's desirable to have the same behaviour of
`regexp.replace` filtering out values that don't match the expression.
The actual implementation and tests for the new helpers in Login Rules
is added in a buddy PR in teleport.e.
This PR also adds documentation for the new functions.
* apply docs grammar suggestions
Co-authored-by: Paul Gottschling <paul.gottschling@goteleport.com>
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Co-authored-by: Paul Gottschling <paul.gottschling@goteleport.com>
