FILE: mapMerge.kt
    public final fun foo(x: R|kotlin/collections/MutableMap<kotlin/String, kotlin/collections/List<kotlin/String>>|): R|kotlin/Unit| {
        R|<local>/x|.R|SubstitutionOverride<kotlin/collections/MutableMap.merge: R|@EnhancedNullability kotlin/collections/List<kotlin/String>?|>|(String(), R|kotlin/collections/listOf|<R|kotlin/String|>(String()), <L> = SAM(merge@fun <anonymous>(a: R|@EnhancedNullability kotlin/collections/List<kotlin/String>|, b: R|@EnhancedNullability kotlin/collections/List<kotlin/String>|): R|@EnhancedNullability kotlin/collections/List<kotlin/String>?| <inline=NoInline>  {
            ^ R|<local>/a|.R|kotlin/collections/plus|<R|kotlin/String|>(R|<local>/b|)
        }
        ))
    }