The requirement for a final ``++when else++`` clause is defensive programming. The clause should either take appropriate action, or contain a suitable comment as to why no action is taken.
== Noncompliant Code Example
----
switch on i { // missing 'when else'
when 2 {
System.debug('when block 2');
}
when -3 {
System.debug('when block -3');
== Compliant Solution
switch on i {
when else {
System.debug('default');
include::../see.adoc[]