JIRA: https://jira.spring.io/browse/INT-3976
The class name in case of `StaticScriptSource` (for inline scripts) is required only for Groovy native engine.
Even if `GroovyScriptParser` provides an explicit `scriptClassName` option, we still can configure
`GroovyScriptExecutingMessageProcessor` with the `StaticScriptSource` from Java without the script class name.
Therefore the logic in the `GroovyScriptParser` isn't robust.
* Remove the `GroovyScriptParser` `scriptClassName` logic altogether
* Change the `GroovyScriptExecutingMessageProcessor` to rely on the Groovy native `scriptClassName` generation
in case of the `scriptSource` is provided without the class name option
* Fix the test for the actual generated script class name
c97ac195a5