diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/JavaToJKTreeBuilder.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/JavaToJKTreeBuilder.kt
index 4667117ff67..61f61f080fb 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/JavaToJKTreeBuilder.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/JavaToJKTreeBuilder.kt
@@ -218,10 +218,8 @@ class JavaToJKTreeBuilder {
                 JKNameIdentifierImpl(name!!),
                 classKind
             ).also {
-                it.declarationList.apply {
-                    declarations = psi.children.mapNotNull {
-                        ElementVisitor(this@DeclarationMapper).apply { it.accept(this) }.resultElement as? JKUniverseDeclaration
-                    }
+                it.declarationList = psi.children.mapNotNull {
+                    ElementVisitor(this@DeclarationMapper).apply { it.accept(this) }.resultElement as? JKUniverseDeclaration
                 }
 
                 bindSymbol(this, it)
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/NewCodeBuilder.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/NewCodeBuilder.kt
index cce76da088e..2434fed3743 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/NewCodeBuilder.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/NewCodeBuilder.kt
@@ -45,10 +45,10 @@ class NewCodeBuilder {
             printer.print(classKindString(universeClass.classKind))
             builder.append(" ")
             printer.print(universeClass.name.value)
-            if (universeClass.declarationList.declarations.isNotEmpty()) {
+            if (universeClass.declarationList.isNotEmpty()) {
                 printer.println("{")
                 printer.pushIndent()
-                universeClass.declarationList.declarations.forEach { it.accept(this, data) }
+                universeClass.declarationList.forEach { it.accept(this, data) }
                 printer.popIndent()
                 printer.println("}")
             }
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/JavaMethodToKotlinFunctionConversion.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/JavaMethodToKotlinFunctionConversion.kt
index 4d1be1f7a73..13a4d859e33 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/JavaMethodToKotlinFunctionConversion.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/JavaMethodToKotlinFunctionConversion.kt
@@ -32,7 +32,7 @@ class JavaMethodToKotlinFunctionConversion : TransformerBasedConversion() {
 
     override fun visitUniverseClass(universeClass: JKUniverseClass) {
         somethingChanged = true
-        universeClass.declarationList.declarations = universeClass.declarationList.declarations.map {
+        universeClass.declarationList = universeClass.declarationList.map {
             if (it is JKJavaMethod) JKKtFunctionImpl(
                 JKJavaPrimitiveTypeImpl.BOOLEAN,
                 it.name,
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/MatchBasedConversion.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/MatchBasedConversion.kt
index 81563b6aa22..84caa4e0194 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/MatchBasedConversion.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/MatchBasedConversion.kt
@@ -6,26 +6,55 @@
 package org.jetbrains.kotlin.j2k.conversions
 
 import org.jetbrains.kotlin.j2k.tree.JKTreeElement
-import org.jetbrains.kotlin.j2k.tree.impl.JKMutableBranchElement
+import org.jetbrains.kotlin.j2k.tree.impl.JKBranchElementBase
 
 abstract class MatchBasedConversion : BaseConversion() {
 
     fun applyRecursive(element: JKTreeElement, func: (JKTreeElement) -> JKTreeElement): JKTreeElement {
-        if (element is JKMutableBranchElement) {
+        if (element is JKBranchElementBase) {
             val iter = element.children.listIterator()
             while (iter.hasNext()) {
                 val child = iter.next()
-                val newChild = func(child)
-                if (child !== newChild) {
-                    onElementChanged(newChild, child)
-                    child.parent = null
-                    newChild.parent = element
-                    iter.set(newChild)
+
+                if (child is List<*>) {
+                    applyRecursiveToList(element, child as List<JKTreeElement>, iter, func)
+                } else if (child is JKTreeElement) {
+                    val newChild = func(child)
+                    if (child !== newChild) {
+                        child.detach(element)
+                        iter.set(newChild)
+                        newChild.attach(element)
+                        onElementChanged(newChild, child)
+                    }
+                } else {
+                    error("unsupported child type: ${child::class}")
                 }
             }
         }
         return element
     }
 
+    private inline fun applyRecursiveToList(
+        element: JKTreeElement,
+        child: List<JKTreeElement>,
+        iter: MutableListIterator<Any>,
+        func: (JKTreeElement) -> JKTreeElement
+    ) {
+
+        val newChild = child.map {
+            func(it)
+        }
+
+        child.forEach { it.detach(element) }
+        iter.set(child)
+        newChild.forEach { it.attach(element) }
+        newChild.zip(child).forEach { (old, new) ->
+            if (old !== new) {
+                onElementChanged(new, old)
+            }
+        }
+    }
+
+
     abstract fun onElementChanged(new: JKTreeElement, old: JKTreeElement)
 }
\ No newline at end of file
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/impl/jk.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/impl/jk.kt
index 9f6e664dca2..de1e27e2919 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/impl/jk.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/impl/jk.kt
@@ -29,28 +29,28 @@ class JKChild<T : JKElement>(val value: Int) : ReadWriteProperty<JKBranchElement
     }
 
     override operator fun setValue(thisRef: JKBranchElementBase, property: KProperty<*>, value: T) {
-        (thisRef.children[this.value] as T).detach()
-        value.attach(thisRef)
+        (thisRef.children[this.value] as T).detach(thisRef)
         thisRef.children[this.value] = value
+        value.attach(thisRef)
     }
 }
 
 class JKListChild<T : JKElement>(val value: Int) : ReadWriteProperty<JKBranchElementBase, List<T>> {
     override operator fun getValue(thisRef: JKBranchElementBase, property: KProperty<*>): List<T> {
-        return thisRef.children.toList() as List<T>
+        return thisRef.children[value] as List<T>
     }
 
     override operator fun setValue(thisRef: JKBranchElementBase, property: KProperty<*>, value: List<T>) {
-        (thisRef.children[this.value] as List<T>).forEach { it.detach() }
-        value.forEach { it.attach(thisRef) }
+        (thisRef.children[this.value] as List<T>).forEach { it.detach(thisRef) }
         thisRef.children[this.value] = value
+        value.forEach { it.attach(thisRef) }
     }
 }
 
 abstract class JKElementBase : JKTreeElement {
     override var parent: JKElement? = null
 
-    final override fun detach() {
+    final override fun detach(from: JKElement) {
         val prevParent = parent
         assert(prevParent != null)
         parent = null
@@ -80,16 +80,18 @@ abstract class JKBranchElementBase : JKElementBase(), JKBranchElement {
     protected var childNum = 0
     protected fun <T : JKTreeElement, U : T> child(v: U): ReadWriteProperty<JKBranchElementBase, T> {
         children.add(childNum, v)
+        v.attach(this)
         return JKChild(childNum++)
     }
 
-    protected inline fun <reified T : JKTreeElement> child(): ReadWriteProperty<JKBranchElementBase, List<T>> {
-        children[childNum] = listOf<T>()
+    protected inline fun <reified T : JKTreeElement> children(): ReadWriteProperty<JKBranchElementBase, List<T>> {
+        children.add(childNum, listOf<T>())
         return JKListChild(childNum++)
     }
 
-    protected inline fun <reified T : JKTreeElement> child(v: List<T>): ReadWriteProperty<JKBranchElementBase, List<T>> {
-        children[childNum] = v
+    protected inline fun <reified T : JKTreeElement> children(v: List<T>): ReadWriteProperty<JKBranchElementBase, List<T>> {
+        children.add(childNum, v)
+        v.forEach { it.attach(this) }
         return JKListChild(childNum++)
     }
 
@@ -113,7 +115,7 @@ class JKClassImpl(modifierList: JKModifierList, name: JKNameIdentifier, override
     override var modifierList by child(modifierList)
     override val valid: Boolean = true
 
-    override var declarationList by child<JKUniverseDeclaration>()
+    override var declarationList by children<JKUniverseDeclaration>()
 
     override fun <R, D> accept(visitor: JKVisitor<R, D>, data: D): R = visitor.visitUniverseClass(this, data)
 }
@@ -122,7 +124,7 @@ class JKClassImpl(modifierList: JKModifierList, name: JKNameIdentifier, override
 class JKNameIdentifierImpl(override val value: String) : JKNameIdentifier, JKElementBase() {}
 
 class JKModifierListImpl(modifiers: List<JKModifier> = emptyList()) : JKModifierList, JKBranchElementBase() {
-    override var modifiers: List<JKModifier> by child(modifiers)
+    override var modifiers: List<JKModifier> by children(modifiers)
     override fun <R, D> accept(visitor: JKVisitor<R, D>, data: D): R = visitor.visitModifierList(this, data)
 }
 
@@ -132,7 +134,7 @@ class JKValueArgumentImpl(type: JKType, override val name: String) : JKValueArgu
 }
 
 class JKBlockImpl(statements: List<JKStatement> = emptyList()) : JKBlock, JKBranchElementBase() {
-    override var statements by child(statements)
+    override var statements by children(statements)
     override fun <R, D> accept(visitor: JKVisitor<R, D>, data: D): R = visitor.visitBlock(this, data)
 }
 
@@ -155,7 +157,7 @@ class JKPostfixExpressionImpl(expression: JKExpression, override var operator: J
 }
 
 class JKExpressionListImpl(expressions: List<JKExpression> = emptyList()) : JKExpressionList, JKBranchElementBase() {
-    override var expressions by child(expressions)
+    override var expressions by children(expressions)
     override fun <R, D> accept(visitor: JKVisitor<R, D>, data: D): R = visitor.visitExpressionList(this, data)
 }
 
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/markers.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/markers.kt
index 2a120b04a2e..85e5236a3da 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/markers.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/markers.kt
@@ -23,7 +23,7 @@ interface JKQualifier
 interface JKElement {
     val parent: JKElement?
 
-    fun detach()
+    fun detach(from: JKElement)
 
     fun attach(to: JKElement)
 }