Injected language completion error

Hello. I'm trying to develop custom language plugin for Rythm template engine.
I implemented Java language injection via LanguageInjector interface.

public class RythmJavaInjector implements LanguageInjector {

     @Override
     public void getLanguagesToInject(@NotNull PsiLanguageInjectionHost psiLanguageInjectionHost, @NotNull InjectedLanguagePlaces injectedLanguagePlaces) {
          if (psiLanguageInjectionHost instanceof RythmJavaCodeLiteral) {
               RythmJavaCodeLiteral literal = (RythmJavaCodeLiteral) psiLanguageInjectionHost;
               injectedLanguagePlaces.addPlace(JavaLanguage.INSTANCE, new TextRange(0,  literal.getTextLength()), "class Test{", "}");
          }
     }
}

Language injection works well, except completion of variable declaration.
When i'm typing something like "BufferedRe.." and press Alt+Enter for autocompletion - i've got an exception:

[1451518]  ERROR - Insight.lookup.impl.LookupImpl - import java.io.BufferedReader;class Test{
     java.io.BufferedReader     
}/class Test{ 
java.lang.AssertionError: import java.io.BufferedReader;class Test{
     java.io.BufferedReader     
}/class Test{
     at com.intellij.injected.editor.DocumentWindowImpl.calculateMinEditSequence(DocumentWindowImpl.java:808)
     at com.intellij.psi.impl.source.tree.injected.InjectedFileViewProvider.rootChanged(InjectedFileViewProvider.java:76)
     at com.intellij.psi.impl.source.PsiFileImpl.subtreeChanged(PsiFileImpl.java:443)
     at com.intellij.psi.impl.source.PsiJavaFileBaseImpl.subtreeChanged(PsiJavaFileBaseImpl.java:82)
     at com.intellij.psi.impl.source.tree.CompositeElement.subtreeChanged(CompositeElement.java:99)
     at com.intellij.psi.impl.source.tree.CompositeElement.rawAddChildren(CompositeElement.java:803)
     at com.intellij.psi.impl.source.tree.CompositeElement.add(CompositeElement.java:877)
     at com.intellij.psi.impl.source.tree.CompositeElement.access$100(CompositeElement.java:51)
     at com.intellij.psi.impl.source.tree.CompositeElement$2.makeChange(CompositeElement.java:653)
     at com.intellij.psi.impl.source.tree.ChangeUtil$1.runInner(ChangeUtil.java:175)
     at com.intellij.pom.impl.PomTransactionBase.run(PomTransactionBase.java:44)
     at com.intellij.pom.core.impl.PomModelImpl.runTransaction(PomModelImpl.java:151)
     at com.intellij.psi.impl.source.tree.ChangeUtil.prepareAndRunChangeAction(ChangeUtil.java:169)
     at com.intellij.psi.impl.source.tree.CompositeElement.addChild(CompositeElement.java:646)
     at com.intellij.psi.impl.source.tree.CompositeElement.addChildren(CompositeElement.java:753)
     at com.intellij.psi.impl.source.codeStyle.CodeEditUtil.addChildren(CodeEditUtil.java:82)
     at com.intellij.psi.impl.source.tree.CompositeElement.addInternal(CompositeElement.java:532)
     at com.intellij.psi.impl.source.tree.java.ImportListElement.addInternal(ImportListElement.java:45)
     at com.intellij.psi.impl.source.JavaStubPsiElement.add(JavaStubPsiElement.java:79)
     at com.intellij.psi.impl.source.codeStyle.ImportHelper.addImport(ImportHelper.java:435)
     at com.intellij.psi.impl.source.codeStyle.JavaCodeStyleManagerImpl.addImport(JavaCodeStyleManagerImpl.java:130)
     at com.intellij.psi.impl.source.PsiJavaFileBaseImpl.importClass(PsiJavaFileBaseImpl.java:426)
     at com.intellij.psi.impl.source.codeStyle.JavaReferenceAdjuster.getClassReferenceToShorten(JavaReferenceAdjuster.java:244)
     at com.intellij.psi.impl.source.codeStyle.JavaReferenceAdjuster.makeShortReference(JavaReferenceAdjuster.java:218)
     at com.intellij.psi.impl.source.codeStyle.JavaReferenceAdjuster.process(JavaReferenceAdjuster.java:110)
     at com.intellij.psi.impl.source.codeStyle.JavaReferenceAdjuster.process(JavaReferenceAdjuster.java:135)
     at com.intellij.psi.impl.source.codeStyle.JavaCodeStyleManagerImpl.shortenClassReferences(JavaCodeStyleManagerImpl.java:80)
     at com.intellij.psi.impl.source.PsiJavaCodeReferenceElementImpl.bindToClass(PsiJavaCodeReferenceElementImpl.java:587)
     at com.intellij.psi.impl.source.PsiJavaCodeReferenceElementImpl.bindToElement(PsiJavaCodeReferenceElementImpl.java:515)
     at com.intellij.codeInsight.completion.JavaCompletionUtil.insertClassReference(JavaCompletionUtil.java:674)
     at com.intellij.codeInsight.lookup.PsiTypeLookupItem.addImportForItem(PsiTypeLookupItem.java:294)
     at com.intellij.codeInsight.completion.JavaClassNameInsertHandler.handleInsert(JavaClassNameInsertHandler.java:95)
     at com.intellij.codeInsight.completion.JavaClassNameInsertHandler.handleInsert(JavaClassNameInsertHandler.java:39)
     at com.intellij.codeInsight.lookup.LookupItem.handleInsert(LookupItem.java:193)
     at com.intellij.codeInsight.completion.CodeCompletionHandlerBase$9.run(CodeCompletionHandlerBase.java:721)
     at com.intellij.openapi.application.impl.ApplicationImpl.runWriteAction(ApplicationImpl.java:984)
     at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.insertItem(CodeCompletionHandlerBase.java:711)
     at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.access$400(CodeCompletionHandlerBase.java:72)
     at com.intellij.codeInsight.completion.CodeCompletionHandlerBase$7.perform(CodeCompletionHandlerBase.java:630)
     at com.intellij.injected.editor.CaretModelWindow$2.perform(CaretModelWindow.java:256)
     at com.intellij.openapi.editor.impl.CaretModelImpl$3.run(CaretModelImpl.java:353)
     at com.intellij.openapi.editor.impl.CaretModelImpl.doWithCaretMerging(CaretModelImpl.java:424)
     at com.intellij.openapi.editor.impl.CaretModelImpl.runForEachCaret(CaretModelImpl.java:347)
     at com.intellij.injected.editor.CaretModelWindow.runForEachCaret(CaretModelWindow.java:253)
     at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.insertItemHonorBlockSelection(CodeCompletionHandlerBase.java:627)
     at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.lookupItemSelected(CodeCompletionHandlerBase.java:568)
     at com.intellij.codeInsight.completion.CompletionProgressIndicator$2.itemSelected(CompletionProgressIndicator.java:110)
     at com.intellij.codeInsight.lookup.impl.LookupImpl.fireItemSelected(LookupImpl.java:1055)
     at com.intellij.codeInsight.lookup.impl.LookupImpl.finishLookup(LookupImpl.java:673)
     at com.intellij.codeInsight.lookup.impl.LookupImpl.finishLookup(LookupImpl.java:612)
     at com.intellij.codeInsight.lookup.impl.actions.ChooseItemAction$Handler.execute(ChooseItemAction.java:73)
     at com.intellij.openapi.editor.actionSystem.EditorActionHandler.doExecute(EditorActionHandler.java:93)
     at com.intellij.openapi.editor.actionSystem.EditorActionHandler.execute(EditorActionHandler.java:125)
     at com.intellij.openapi.editor.actionSystem.EditorAction$1.run(EditorAction.java:83)
     at com.intellij.openapi.command.impl.CommandProcessorImpl.executeCommand(CommandProcessorImpl.java:124)
     at com.intellij.openapi.editor.actionSystem.EditorAction.actionPerformed(EditorAction.java:94)
     at com.intellij.openapi.editor.actionSystem.EditorAction.actionPerformed(EditorAction.java:68)
     at com.intellij.openapi.keymap.impl.IdeKeyEventDispatcher$3.performAction(IdeKeyEventDispatcher.java:564)
     at com.intellij.openapi.keymap.impl.IdeKeyEventDispatcher.processAction(IdeKeyEventDispatcher.java:611)
     at com.intellij.openapi.keymap.impl.IdeKeyEventDispatcher.inInitState(IdeKeyEventDispatcher.java:463)
     at com.intellij.openapi.keymap.impl.IdeKeyEventDispatcher.dispatchKeyEvent(IdeKeyEventDispatcher.java:206)
     at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:493)
     at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:335)
     at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
     at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
[1451518]  ERROR - Insight.lookup.impl.LookupImpl - IntelliJ IDEA 13.1.1  Build #IC-135.480 
[1451518]  ERROR - Insight.lookup.impl.LookupImpl - JDK: 1.8.0-ea 
[1451518]  ERROR - Insight.lookup.impl.LookupImpl - VM: Java HotSpot(TM) 64-Bit Server VM 
[1451518]  ERROR - Insight.lookup.impl.LookupImpl - Vendor: Oracle Corporation 
[1451518]  ERROR - Insight.lookup.impl.LookupImpl - OS: Linux 
[1451518]  ERROR - Insight.lookup.impl.LookupImpl - Last Action: EditorChooseLookupItem 
[1451518]  ERROR - Insight.lookup.impl.LookupImpl - Current Command: Choose Lookup Item 

But if i change injection prefix from  "class Test{" to "" - autocompletion works without exceptions.
Tell me please, what I'm doing wrong