void setConversionMapping(PsiExpression expression, Object obj) {
    if (myConversions.get(expression) != null) {
      return;
    }

    if (obj instanceof TypeConversionDescriptorBase) {
      ((TypeConversionDescriptorBase)obj).setRoot(myCurrentRoot);
    }
    myConversions.put(expression, obj);
  }
void setConversionMapping(PsiExpression expression, Object obj)