Bug #102435 java.time.LocalDateTime cannot be cast to class java.lang.String

Description:
I'm using Keycloak with Liquibase and since MySQL Connector/J version 8.0.23 there is a ClassCastException.

This is different to https://bugs.mysql.com/bug.php?id=101413 where
"cannot be cast to java.sql.Timestamp" occured.
Here we have a:
"cannot be cast to class java.lang.String"

related part of stack trace:
Caused by: java.lang.ClassCastException: class java.time.LocalDateTime cannot be cast to class java.lang.String (java.time.LocalDateTime and java.lang.String are in module java.base of loader 'bootstrap')
        at org.liquibase//liquibase.changelog.StandardChangeLogHistoryService.getRanChangeSets(StandardChangeLogHistoryService.java:287)
        at org.liquibase//liquibase.database.AbstractJdbcDatabase.getRanChangeSetList(AbstractJdbcDatabase.java:1124)
        at org.liquibase//liquibase.changelog.DatabaseChangeLog.validate(DatabaseChangeLog.java:257)
        at org.liquibase//liquibase.Liquibase.listUnrunChangeSets(Liquibase.java:1189)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        ......

All products using Liquibase seems to have this problem and there are two issues on Github:
https://github.com/liquibase/liquibase/issues/1639
https://github.com/liquibase/liquibase/issues/1647

But both where closed in a manner, that the problem seems to be in MySQL Connector/J

How to repeat:
Install Keycloak and use MySQL Module with Connector/J
In version <= 8.0.22 --> it's ok
in version == 8.0.23 --> ClassCastException: class java.time.LocalDateTime cannot be cast to class java.lang.String

Suggested fix:
If you are not willing to change back to old behaviour, state it in release note somehow as incompatible change.

Hi Patrik,

Yes, that's the intended change, and we already added the note to the changelog https://dev.mysql.com/doc/relnotes/connector-j/8.0/en/news-8-0-23.html:

Functionality Added or Changed -> Important -> "Also, with the implementation of the new mechanism, a getObject(columnIndex) call on a DATETIME column returns a LocalDateTime object now instead of a String. To receive a String like before, use getObject(columnIndex, String.class) instead."

This change breaks the MySQL implementation in Adobe ColdFusion.

For query resultsets, a java.time.LocalDateTime object is returned instead of a datetime string.

Reverting to 8.0.22 fixed this problem.

I used Spring Boot Parent Starter 2.4.3, which contains MySQL 8.0.23.

Scenario 1:
A clean database + start Spring Boot project = OK.

Scenario 2:
A clean database + start Spring Boot project = OK.
Shut down project.
Database has schema with data + start Spring Boot project = fail. Same problem as OP.

Solution:
Revert Spring Boot Starter Parent to 2.4.2.
Scenario 1:
Start and stop the project as many times as you would like. It will always work.