5.6.15 throwing java.lang.ClassCastException error when using LdapTemplate

Steps to reproduce the problem

1. Add a custom post-function in the workflow transition and using the code below:

   import org.springframework.ldap.core.LdapTemplate
   
   LdapTemplate test = new LdapTemplate()
   log.warn test
   

2. Save it and publish the workflow.
3. Performed a transition to trigger the post-function and logs showing the following errors:

   2020-05-29 05:27:37,622 http-nio-8080-exec-15 ERROR admin 327x1011x1 172l8jw 172.17.0.1 /secure/WorkflowUIDispatcher.jspa [c.o.s.jira.workflow.AbstractScriptWorkflowFunction] Script function failed on issue: AA-14, actionId: 11, file: null
   java.lang.ClassCastException: org.springframework.core.convert.support.DefaultConversionService cannot be cast to org.springframework.core.convert.support.GenericConversionService
   	at org.springframework.ldap.odm.typeconversion.impl.ConversionServiceConverterManager.<init>(ConversionServiceConverterManager.java:45)
   	at org.springframework.ldap.odm.core.impl.DefaultObjectDirectoryMapper.createDefaultConverterManager(DefaultObjectDirectoryMapper.java:82)
   	at org.springframework.ldap.odm.core.impl.DefaultObjectDirectoryMapper.<init>(DefaultObjectDirectoryMapper.java:73)
   	at org.springframework.ldap.core.LdapTemplate.<init>(LdapTemplate.java:93)
   	at Script4.run(Script4.groovy:3)
   

In the execution history log, it doesn't record any error or success icon.

Note

Aside from workflow, the issue can also be seen on Jobs and Listener

The script is working in the Script Console.