private void clearIfLookupAndArrangerPrefixesMatch() {
    boolean isCompletionArranger = myArranger instanceof CompletionLookupArrangerImpl;
    if (isCompletionArranger) {
      final String lastLookupArrangersPrefix = ((CompletionLookupArrangerImpl)myArranger).getLastLookupPrefix();
      if (lastLookupArrangersPrefix != null && !lastLookupArrangersPrefix.equals(getAdditionalPrefix())) {
        LOG.trace("prefixes don't match, do not clear lookup additional prefix");
      }
      else {
        myOffsets.clearAdditionalPrefix();
      }
    }
    else {
      myOffsets.clearAdditionalPrefix();
    }
  }
private void clearIfLookupAndArrangerPrefixesMatch()