New J2K: remove static modifier for the case when member is converted without containing class

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

@@ -78,6 +78,7 @@ object ConversionsRunner {
             +StaticsToCompanionExtractConversion()
             +InterfaceWithFieldConversion()
             +ClassToObjectPromotionConversion(context)
+            +RemoveWrongExtraModifiersForSingleFunctionsConversion()
             +MethodReferenceToLambdaConversion(context)
             +BuiltinMembersConversion(context)
             +ImplicitCastsConversion(context)

nj2k/src/org/jetbrains/kotlin/nj2k/conversions/RemoveWrongExtraModifiersForSingleFunctionsConversion.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.conversions
+
+import org.jetbrains.kotlin.nj2k.tree.*
+
+class RemoveWrongExtraModifiersForSingleFunctionsConversion : RecursiveApplicableConversionBase() {
+    override fun applyToElement(element: JKTreeElement): JKTreeElement {
+        if (element !is JKExtraModifiersOwner) return recurse(element)
+        if (element.parentOfType<JKClass>() == null) {
+            element.elementByModifier(ExtraModifier.STATIC)?.also { modifierElement ->
+                element.extraModifierElements -= modifierElement
+            }
+        }
+        return recurse(element)
+    }
+}