[Bug]: The source transform to read from [1] couldn't be found

### Apache Hop version?

2.10

### Java version?

17

### Operating system

Windows

### What happened?

when I use "User defined Java class",it is show "The source transform to read from [laststep] couldn't be found" when i click "Test class", But i hava already setting laststep to "Info transforms"

### Issue Priority

Priority: 0

### Issue Component

Component: Hop Gui

Reproduce the problem in Hop 2.10 on Windows with Java 17 using the User defined Java class transform and its Test class action. Start by tracing how the Hop GUI resolves the configured source transform, then verify that a source set to the last step resolves successfully and the class test completes without the error.

Written by the indexing model from the issue text.