Use SCIM filter expressions to define how the provisioner matches existing users in the target application to users in the identity store. The expression overrides the default filter expression that is set by the User Identifier field.
The user filter expression contains the attribute name, the operation, and the attribute
value. The attribute value is represented by "%s" in the
expression.
The “%s” variable stores the value of the user identifier. The value
that you select in the User Identifier list, such as userName or
workEmail, is used in the User Filter Expression and replaces the
contents of the "%s" variable.
Example filter expressions:
username Eq "%s"email Co "%s"
For more information, see the Filtering section in the SCIM 2.0 specification RFC 7644.