Obsolete timeline changes

How to handle obsolete timeline Changes - either ignoring them or upgrading them to a newer version

We have two kinds of obsolete Changes:

1. The Change can be ignored (we either don't use it at all or we push new changes that replace the old one)

2. The Change should be upgraded to a newer version

The Change can be ignored

1. Delete the obsolete C# Change class and the related C# code

2. Create the list of obsolete changes

3. Register this list in the Projector's class constructor:

   
4. Add a new Handle method for SerializedChange to the Projector class:

   
5. Add a new When method to the State class, it will intercept all obsolete changes:

   

The Change should be upgraded to a new version

Lets assume we have the change AttemptStarted1 and it needs to be marked as obsolete because we introduced a new change AttemptStarted2

1. Make AttemptStarted1 as a private nested class of AttemptStarted2 and implement a new Upgrade method that will convert AttemptStarted1 to AttemptStarted2:

   
2. Delete all functionality related to AttemptStarted1

3. In the AttemptChangeProjector register AttemptStarted1 as an obsolete change:

   
4. Add a new Handle method in the Projector class that will upgrade AttemptStarted1 to AttemptStarted2 and call Handle for AttemptStarted2:

   
5. Add a new When method to AttemptState that will upgrade AttemptStarted1 to AttemptStarted2 and call When for AttemptStarted2: