Checking classes
Is Structurally modifiable class Main$C1 true
Is Structurally modifiable class Main$C2 true
Is Structurally modifiable class Main$C3 true
Setting C2 as having pointer-ids used and checking classes
Is Structurally modifiable class Main$C1 false
Is Structurally modifiable class Main$C2 false
Is Structurally modifiable class Main$C3 true