diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/JavaToJKTreeBuilder.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/JavaToJKTreeBuilder.kt
index f7dc00d5d52..bd66aa15cdb 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/JavaToJKTreeBuilder.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/JavaToJKTreeBuilder.kt
@@ -291,10 +291,10 @@ class JavaToJKTreeBuilder(var symbolProvider: JKSymbolProvider) {
                 this.referencedTypes.map { with(expressionTreeMapper) { JKTypeElementImpl(it.toJK(symbolProvider, Nullability.NotNull)) } }
 
             val implTypes = this.implementsList?.mapTypes().orEmpty()
-            val extTypes = this.extendsList?.mapTypes().orEmpty()
+            val extensionType = this.extendsList?.mapTypes().orEmpty()
             return JKClassImpl(
                 JKNameIdentifierImpl(name!!),
-                JKInheritanceInfoImpl(extTypes + implTypes),
+                JKInheritanceInfoImpl(extensionType, implTypes),
                 classKind,
                 typeParameterList?.toJK() ?: JKTypeParameterListImpl(),
                 createClassBody(),
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/NewCodeBuilder.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/NewCodeBuilder.kt
index accdcfaa0c3..3e8bdacc3d8 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/NewCodeBuilder.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/NewCodeBuilder.kt
@@ -185,18 +185,10 @@ class NewCodeBuilder {
             val primaryConstructor = klass.primaryConstructor()
             primaryConstructor?.accept(this)
 
-            if (klass.inheritance.inherit.isNotEmpty()) {
-                printer.printWithNoIndent(" : ")
 
-                val delegationCall = primaryConstructor?.delegationCall as? JKDelegationConstructorCall
-                renderList(klass.inheritance.inherit) {
-                    it.accept(this)
-                    if (delegationCall != null && delegationCall.isCallOfConstructorOf(it.type)) {
-                        printer.par {
-                            delegationCall.arguments.accept(this)
-                        }
-                    }
-                }
+            if (klass.inheritance.present()) {
+                printer.printWithNoIndent(" : ")
+                klass.inheritance.accept(this)
             }
 
             //TODO should it be here?
@@ -205,6 +197,36 @@ class NewCodeBuilder {
             klass.classBody.accept(this)
         }
 
+        override fun visitInheritanceInfo(inheritanceInfo: JKInheritanceInfo) {
+            val parentClass = inheritanceInfo.parentOfType<JKClass>()!!
+            val isInInterface = parentClass.classKind == JKClass.ClassKind.INTERFACE
+            val extendTypes = inheritanceInfo.extends.map { it.type.updateNullability(Nullability.NotNull) }
+            val implementTypes = inheritanceInfo.implements.map { it.type.updateNullability(Nullability.NotNull) }
+            if (isInInterface) {
+                renderList(extendTypes) { renderType(it) }
+            } else {
+                extendTypes.singleOrNull()?.also {
+                    renderType(it)
+                    val delegationCall =
+                        parentClass
+                            .primaryConstructor()
+                            ?.delegationCall
+                            ?.let { it as? JKDelegationConstructorCall }
+                    if (delegationCall != null) {
+                        printer.par { delegationCall.arguments.accept(this) }
+                    } else {
+                        printer.printWithNoIndent("()")
+                    }
+                }
+            }
+
+            if (implementTypes.isNotEmpty() && extendTypes.size == 1) {
+                printer.printWithNoIndent(", ")
+            }
+            renderList(implementTypes) { renderType(it) }
+        }
+
+
         private fun renderEnumConstants(enumConstants: List<JKEnumConstant>) {
             renderList(enumConstants) {
                 it.accept(this)
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/InsertDefaultPrimaryConstructorConversion.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/InsertDefaultPrimaryConstructorConversion.kt
index e3383d0d78a..0b38f4a4c03 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/InsertDefaultPrimaryConstructorConversion.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/InsertDefaultPrimaryConstructorConversion.kt
@@ -28,15 +28,15 @@ class InsertDefaultPrimaryConstructorConversion(private val context: ConversionC
 
         element.classBody.declarations += constructor
 
-        val superClassSymbol = element.inheritance.inherit.map { it.type }
-            .filterIsInstance<JKClassType>()
-            .mapNotNull { (it.classReference as? JKClassSymbol) }
-            .firstOrNull { it.kind == JKClass.ClassKind.CLASS }
+        val superClassSymbol =
+            (element.inheritance.extends.singleOrNull() as? JKClassType)?.classReference
 
         if (superClassSymbol is JKUniverseClassSymbol) {
             val superClass = recurse(superClassSymbol.target)
             val superConstructor = context.symbolProvider.provideUniverseSymbol(
-                superClass.declarationList.single { it is JKKtConstructor && it.parameters.isEmpty() } as JKMethod
+                superClass.declarationList.singleOrNull { it is JKKtConstructor && it.parameters.isEmpty() } as? JKMethod ?: return recurse(
+                    element
+                )
             )
             constructor.delegationCall = JKDelegationConstructorCallImpl(superConstructor, JKSuperExpressionImpl(), JKExpressionListImpl())
         }
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/StaticsToCompanionExtractConversion.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/StaticsToCompanionExtractConversion.kt
index e6e9f31fda2..ac267502318 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/StaticsToCompanionExtractConversion.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/StaticsToCompanionExtractConversion.kt
@@ -40,7 +40,7 @@ class StaticsToCompanionExtractConversion : RecursiveApplicableConversionBase()
 
         return JKClassImpl(
             JKNameIdentifierImpl(""),
-            JKInheritanceInfoImpl(emptyList()),
+            JKInheritanceInfoImpl(emptyList(), emptyList()),
             JKClass.ClassKind.COMPANION,
             JKTypeParameterListImpl(),
             JKClassBodyImpl(),
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 f6a0c3caf16..d98858c35e0 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/impl/jk.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/impl/jk.kt
@@ -377,8 +377,12 @@ class JKLambdaExpressionImpl(
     override fun <R, D> accept(visitor: JKVisitor<R, D>, data: D): R = visitor.visitLambdaExpression(this, data)
 }
 
-class JKInheritanceInfoImpl(implements: List<JKTypeElement>) : JKInheritanceInfo, JKBranchElementBase(), PsiOwner by PsiOwnerImpl() {
-    override val inherit: List<JKTypeElement> by children(implements)
+class JKInheritanceInfoImpl(
+    extends: List<JKTypeElement>,
+    implements: List<JKTypeElement>
+) : JKInheritanceInfo, JKBranchElementBase(), PsiOwner by PsiOwnerImpl() {
+    override var extends: List<JKTypeElement> by children(extends)
+    override var implements: List<JKTypeElement> by children(implements)
 
     override fun <R, D> accept(visitor: JKVisitor<R, D>, data: D): R = visitor.visitInheritanceInfo(this, data)
 }
diff --git a/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/jk.kt b/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/jk.kt
index acbd5354580..381db5ebcb7 100644
--- a/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/jk.kt
+++ b/j2k/newSrc/org/jetbrains/kotlin/j2k/tree/jk.kt
@@ -68,9 +68,13 @@ val JKClass.declarationList: List<JKDeclaration>
 
 
 interface JKInheritanceInfo : JKTreeElement, JKBranchElement {
-    val inherit: List<JKTypeElement>
+    var extends: List<JKTypeElement>
+    var implements: List<JKTypeElement>
 }
 
+fun JKInheritanceInfo.present(): Boolean =
+    extends.isNotEmpty() || implements.isNotEmpty()
+
 interface JKAnnotationList : JKTreeElement {
     var annotations: List<JKAnnotation>
 }