Re : precondition is not working for schema

Caused by: liquibase.exception.ValidationFailedException: Validation Failed:
   4 change sets check sum

There is a mismatch between old checksum and new checksum value.

From the below stackoverflow post, I come to know that clearChecksum will clean the checksum and recompute every time.
https://stackoverflow.com/questions/34655157/how-to-solve-liquibase-checksum-validation-fail-after-liquibase-upgrade/34661256

That is what I am trying to do.

Please suggest my approach is correct or not ?

Note : I am not getting checksum error now,  If you need the same to fully understand please let me 
know, I will try to reproduce and post it here.

Thanks
Senthil