Replace deprecated usages of max/min with maxOrNull/minOrNull

nj2k/src/org/jetbrains/kotlin/nj2k/BaseConversion.kt

@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.nj2k
 
-
 import org.jetbrains.kotlin.nj2k.tree.JKTreeElement
 import org.jetbrains.kotlin.nj2k.types.JKTypeFactory
 
@@ -25,6 +24,6 @@ interface SequentialBaseConversion : Conversion {
     fun runConversion(treeRoot: JKTreeElement, context: NewJ2kConverterContext): Boolean
 
     override fun runConversion(treeRoots: Sequence<JKTreeElement>, context: NewJ2kConverterContext): Boolean {
-        return treeRoots.asSequence().map { runConversion(it, context) }.max() ?: false
+        return treeRoots.maxOfOrNull { runConversion(it, context) } ?: false
     }
-}
+}