diff --git a/nj2k/src/org/jetbrains/kotlin/nj2k/JavaToJKTreeBuilder.kt b/nj2k/src/org/jetbrains/kotlin/nj2k/JavaToJKTreeBuilder.kt
index f134fbaf991..9fb93603cc7 100644
--- a/nj2k/src/org/jetbrains/kotlin/nj2k/JavaToJKTreeBuilder.kt
+++ b/nj2k/src/org/jetbrains/kotlin/nj2k/JavaToJKTreeBuilder.kt
@@ -171,7 +171,7 @@ class JavaToJKTreeBuilder constructor(
 
         fun PsiAssignmentExpression.toJK(): JKJavaAssignmentExpression {
             return JKJavaAssignmentExpressionImpl(
-                lExpression.toJK() as? JKAssignableExpression ?: error("Its possible? ${lExpression.toJK().prettyDebugPrintTree()}"),
+                lExpression.toJK() as JKAssignableExpression,
                 rExpression.toJK(),
                 operationSign.tokenType.toJK()
             ).also {
diff --git a/nj2k/src/org/jetbrains/kotlin/nj2k/conversions/TransformerBasedConversion.kt b/nj2k/src/org/jetbrains/kotlin/nj2k/conversions/TransformerBasedConversion.kt
deleted file mode 100644
index 8b6d1a26d29..00000000000
--- a/nj2k/src/org/jetbrains/kotlin/nj2k/conversions/TransformerBasedConversion.kt
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
- * Copyright 2010-2017 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.kotlin.nj2k.conversions
-
-import org.jetbrains.kotlin.nj2k.NewJ2kConverterContext
-import org.jetbrains.kotlin.nj2k.tree.JKTreeElement
-import org.jetbrains.kotlin.nj2k.tree.visitors.JKVisitorVoid
-
-abstract class TransformerBasedConversion : SequentialBaseConversion, JKVisitorVoid {
-    protected var somethingChanged = false
-
-    override fun runConversion(treeRoot: JKTreeElement, context: NewJ2kConverterContext): Boolean {
-        somethingChanged = false
-        treeRoot.accept(this, null)
-        return somethingChanged
-    }
-}
\ No newline at end of file
diff --git a/nj2k/src/org/jetbrains/kotlin/nj2k/tree/DebugTreePrinter.kt b/nj2k/src/org/jetbrains/kotlin/nj2k/tree/DebugTreePrinter.kt
deleted file mode 100644
index 97c5d3d9a58..00000000000
--- a/nj2k/src/org/jetbrains/kotlin/nj2k/tree/DebugTreePrinter.kt
+++ /dev/null
@@ -1,115 +0,0 @@
-/*
- * Copyright 2010-2017 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.kotlin.nj2k.tree
-
-import org.jetbrains.kotlin.nj2k.tree.impl.JKClassSymbol
-import org.jetbrains.kotlin.nj2k.tree.impl.JKSymbol
-import org.jetbrains.kotlin.nj2k.tree.visitors.JKVisitorVoid
-import org.jetbrains.kotlin.utils.Printer
-
-private class DebugTreePrinter : JKVisitorVoid {
-    internal val stringBuilder = StringBuilder()
-    private val printer = Printer(stringBuilder)
-
-    override fun visitTreeElement(treeElement: JKTreeElement) {
-        printer.println(treeElement.describe(), " [")
-        printer.indented {
-            treeElement.acceptChildren(this, null)
-        }
-        printer.println("]")
-    }
-
-    override fun visitNameIdentifier(nameIdentifier: JKNameIdentifier) {
-        printer.println(nameIdentifier.describe(), "(\"", nameIdentifier.value, "\")")
-    }
-
-    override fun visitJavaMethod(javaMethod: JKJavaMethod) {
-        printer.print(javaMethod.modifierElements().joinToString(" ") { it.modifier.text })
-        printer.println(javaMethod.describe(), " [")
-        printer.indented {
-            javaMethod.block.accept(this, null)
-            javaMethod.parameters.forEach { it.accept(this, null) }
-        }
-        printer.println("]")
-    }
-
-    override fun visitExpressionStatement(expressionStatement: JKExpressionStatement) {
-        printer.println(expressionStatement.describe(), " [")
-        printer.indented {
-            expressionStatement.acceptChildren(this, null)
-        }
-        printer.println("]")
-    }
-
-    override fun visitQualifiedExpression(qualifiedExpression: JKQualifiedExpression) {
-        printer.println(qualifiedExpression.describe(), " [")
-        printer.indented {
-            qualifiedExpression.acceptChildren(this, null)
-        }
-        printer.println("]")
-    }
-
-    override fun visitBlock(block: JKBlock) {
-        printer.println(block.describe(), " [")
-        printer.indented {
-            block.acceptChildren(this, null)
-        }
-        printer.println("]")
-    }
-
-    override fun visitTypeElement(typeElement: JKTypeElement) {
-        val type = typeElement.type
-        printer.println(type.classNameWithoutJK(), " \"")
-        printer.indented {
-            if (type is JKClassType) {
-                printer.println((type.classReference as? JKClassSymbol)?.fqName ?: type.classReference.let { it::class })
-            }
-            if (type is JKJavaPrimitiveType) {
-                printer.println(type.jvmPrimitiveType.javaKeywordName)
-            }
-        }
-        printer.println("\"")
-    }
-
-    override fun visitFieldAccessExpression(fieldAccessExpression: JKFieldAccessExpression) {
-        printer.print(fieldAccessExpression.describe(), "(")
-        printSymbol(fieldAccessExpression.identifier)
-        printer.printlnWithNoIndent(")")
-    }
-
-    fun printSymbol(symbol: JKSymbol) {
-        val target = symbol.target
-        if (target is JKTreeElement) {
-            printer.printWithNoIndent(target.describe())
-        } else {
-            printer.printWithNoIndent("Psi")
-        }
-    }
-}
-
-private fun JKTreeElement.describe(): String = this.classNameWithoutJK() + "@${this.hashCode().toString(16)}"
-private fun JKTreeElement.classNameWithoutJK(): String = this.javaClass.simpleName.removePrefix("JK")
-private fun JKType.classNameWithoutJK(): String = this.javaClass.simpleName.removePrefix("JK")
-
-private inline fun Printer.indented(block: () -> Unit) {
-    this.pushIndent()
-    block()
-    this.popIndent()
-}
-
-
-fun JKTreeElement.prettyDebugPrintTree(): String = DebugTreePrinter().apply { accept(this, null) }.stringBuilder.toString()
\ No newline at end of file