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NetBeans IDE provides the Options window (menu Tools → Options or NetBeans → Preferences on MacOS) that allows the user to customize it. You can provide any customizations for your language support in the Options window, too. E.g. you could allow the user to provide the path to the Kotlin compiler. See e.g. rust/rust.cargo module that allows the user to provide the path to cargo for Rust projects.
The NetBeans Options Window Module Tutorial explains how you could do that.
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