Content assist to commit message

Hi,

I want to extends content assist of vcs commit message dialog.

What I did is

* add `completion.contributor language="any"` to plugin.xml
* create custom `CompletionContributor`
* call `extend()` in constructor

For now, I implemented following code. This code hit breakpoints if I do content assist at Editor, but not works for Commit Dialog.

```

init {
    extend(CompletionType.BASIC, TruePattern(), object : CompletionProvider<CompletionParameters>() {
        override fun addCompletions(parameters: CompletionParameters, context: ProcessingContext?, result: CompletionResultSet) {
            println()
        }
    })
}

override fun fillCompletionVariants(parameters: CompletionParameters, result: CompletionResultSet) {
    super.fillCompletionVariants(parameters, result)
}

private class TruePattern : ElementPattern<PsiElement> {
    override fun accepts(o: Any?): Boolean {
        return true
    }

    override fun accepts(o: Any?, context: ProcessingContext): Boolean {
        return true
    }

    override fun getCondition(): ElementPatternCondition<PsiElement> {
        return ElementPatternCondition(object : InitialPatternCondition<PsiElement>(PsiElement::class.java) {
            override fun accepts(o: Any?, context: ProcessingContext?): Boolean {
                return true
            }
        })
    }
}

```

Is there a way to content assist to Commit Message?

Thanks, in advance.