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

The script is working in the Script Console.