Do not skip "...on" in all$ methods for union and interface projections

[sdaurea]

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Description

Related to #1375

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Changes were made to:

• Codegen library - Java
• Codegen library - Kotlin
• Codegen library - Scala
• Maven plugin
• Gradle plugin
• SBT plugin

[jxnu-liguobin]

When you open it, does it mean you are in need of it? This is great. Can you test if it really meets the requirements? (Test its results at runtime ) Thank you!

Because I skipped it directly to avoid testing the union.

[alaa-nassef]

When you open it, does it mean you are in need of it? This is great. Can you test if it really meets the requirements? (Test its results at runtime ) Thank you!

Because I skipped it directly to avoid testing the union.

@jxnu-liguobin to answer your first question, yes, we do need this in the project we're working on and it is currently kind of a blocker for us. As for testing results at runtime, we were planning to do this, but we have to publish our own version first and use it instead, which would need some more time

[kobylynskyi]

@alaa-nassef looks good!. Thanks for the contribution!

[derwild]

I'm not sure about your release schedule, but can you already say, when the 5.9.0 maven plugin will be released?

[kobylynskyi]

@derwild targeting this week.

[derwild]

@kobylynskyi nice, thank you