Reference converter and completion data

Hi all,

It seems that I miss somethign obvious.   I annotated   DOM object methods with:

  /**
     * Returns the value of the from child.
     *
     * @return the value of the from child.
     */
    @NotNull
    @Referencing(SequenceFromReferenceConverter.class)
    GenericAttributeValue<String> getFrom();


    /**
     * Returns the value of the to child.
     *
     * @return the value of the to child.
     */
    @NotNull
    @Referencing(SequenceToReferenceConverter.class)
    GenericAttributeValue<String> getTo();

[  25616]  ERROR - ight.completion.CompletionData - Null string for object: ******************.psi.EventNameReference@2b9f8f3d of class class *******************.psi.EventNameReference 
java.lang.Throwable
     at com.intellij.openapi.diagnostic.Logger.error(Logger.java:54)
     at com.intellij.codeInsight.completion.CompletionData.objectToLookupItem(CompletionData.java:255)
     at com.intellij.codeInsight.completion.CompletionData.addLookupItem(CompletionData.java:273)
     at com.intellij.codeInsight.completion.CompletionData.completeReference(CompletionData.java:331)
     at com.intellij.codeInsight.completion.CompletionVariant.addReferenceCompletions(CompletionVariant.java:181)
     at com.intellij.codeInsight.completion.CompletionData.completeReference(CompletionData.java:112)
     at com.intellij.codeInsight.completion.LegacyCompletionContributor$1.consume(LegacyCompletionContributor.java:72)
     at com.intellij.codeInsight.completion.LegacyCompletionContributor$1.consume(LegacyCompletionContributor.java:68)
     at com.intellij.codeInsight.completion.LegacyCompletionContributor.a(LegacyCompletionContributor.java:123)
     at com.intellij.codeInsight.completion.LegacyCompletionContributor.processReferences(LegacyCompletionContributor.java:106)
 

I used @NameValue annotation but no  change..... What do I miss? @Presentation ? Shall I implement presentation provider by reference object itself ?