void OnBeforeSerialize()

Unity invokes the callback on an object before serializing it. In this callback, you can transform your data into something Unity understands. For example, to serialize a C# , copy the data from the object into an array of keys and an array of values.

Refer to Custom serialization in the Manual for more information.

Note: Unity calls before recompiling scripts in a domain reload, so any changes made to code in this method won't take effect until the second invocation of the callback following the change, in other words after a full serialization and domain reload cycle. For more information, refer to Details of disabling domain and scene reload in the Manual.