diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/impl/JavaPackageImpl.java b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/impl/JavaPackageImpl.java
deleted file mode 100644
index d5e1119758c..00000000000
--- a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/impl/JavaPackageImpl.java
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * Copyright 2010-2014 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.jetbrains.jet.lang.resolve.java.structure.impl;
-
-import com.intellij.openapi.util.Condition;
-import com.intellij.psi.PsiClass;
-import com.intellij.psi.PsiPackage;
-import com.intellij.util.containers.ContainerUtil;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.jet.lang.resolve.java.structure.JavaClass;
-import org.jetbrains.jet.lang.resolve.java.structure.JavaPackage;
-import org.jetbrains.jet.lang.resolve.name.FqName;
-
-import java.util.Collection;
-
-import static org.jetbrains.jet.lang.resolve.java.structure.impl.JavaElementCollectionFromPsiArrayUtil.classes;
-import static org.jetbrains.jet.lang.resolve.java.structure.impl.JavaElementCollectionFromPsiArrayUtil.packages;
-
-public class JavaPackageImpl extends JavaElementImpl<PsiPackage> implements JavaPackage {
-    public JavaPackageImpl(@NotNull PsiPackage psiPackage) {
-        super(psiPackage);
-    }
-
-    @Override
-    @NotNull
-    public Collection<JavaClass> getClasses() {
-        return classes(ContainerUtil.filter(getPsi().getClasses(), new Condition<PsiClass>() {
-            @Override
-            public boolean value(PsiClass aClass) {
-                return aClass.getName() != null;
-            }
-        }));
-    }
-
-    @Override
-    @NotNull
-    public Collection<JavaPackage> getSubPackages() {
-        return packages(getPsi().getSubPackages());
-    }
-
-    @Override
-    @NotNull
-    public FqName getFqName() {
-        return new FqName(getPsi().getQualifiedName());
-    }
-}
diff --git a/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/impl/JavaPackageImpl.kt b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/impl/JavaPackageImpl.kt
new file mode 100644
index 00000000000..2e977e1c67f
--- /dev/null
+++ b/compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/impl/JavaPackageImpl.kt
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.lang.resolve.java.structure.impl
+
+import com.intellij.openapi.util.Condition
+import com.intellij.psi.PsiClass
+import com.intellij.psi.PsiPackage
+import com.intellij.util.containers.ContainerUtil
+import org.jetbrains.jet.lang.resolve.java.structure.JavaClass
+import org.jetbrains.jet.lang.resolve.java.structure.JavaPackage
+import org.jetbrains.jet.lang.resolve.name.FqName
+
+import org.jetbrains.jet.lang.resolve.java.structure.impl.JavaElementCollectionFromPsiArrayUtil.classes
+import org.jetbrains.jet.lang.resolve.java.structure.impl.JavaElementCollectionFromPsiArrayUtil.packages
+
+public class JavaPackageImpl(psiPackage: PsiPackage) : JavaElementImpl<PsiPackage>(psiPackage), JavaPackage {
+
+    override fun getClasses() = classes(getPsi().getClasses().filter { it.getName() != null })
+
+    override fun getSubPackages() = packages(getPsi().getSubPackages())
+
+    override fun getFqName() = FqName(getPsi().getQualifiedName())
+}
diff --git a/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaPackage.java b/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaPackage.kt
similarity index 63%
rename from core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaPackage.java
rename to core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaPackage.kt
index 892e7685dfc..9d09dd0f21c 100644
--- a/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaPackage.java
+++ b/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaPackage.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2013 JetBrains s.r.o.
+ * Copyright 2010-2014 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,24 +14,18 @@
  * limitations under the License.
  */
 
-package org.jetbrains.jet.lang.resolve.java.structure;
+package org.jetbrains.jet.lang.resolve.java.structure
 
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.jet.lang.resolve.name.FqName;
+import org.jetbrains.jet.lang.resolve.name.FqName
 
-import java.util.Collection;
-
-public interface JavaPackage extends JavaElement {
+public trait JavaPackage : JavaElement {
     /**
      * NOTE: do not use this method directly
      * @see org.jetbrains.jet.lang.resolve.java.resolver.DescriptorResolverUtils#getClassesInPackage(JavaPackage)
      */
-    @NotNull
-    Collection<JavaClass> getClasses();
+    public fun getClasses(): Collection<JavaClass>
 
-    @NotNull
-    Collection<JavaPackage> getSubPackages();
+    public fun getSubPackages(): Collection<JavaPackage>
 
-    @NotNull
-    FqName getFqName();
+    public fun getFqName(): FqName
 }