private void addIndexedDateAttributes(Document document, ITask task) {
   addIndexedAttribute(
       document, DefaultTaskSchema.getInstance().DATE_COMPLETION, task.getCompletionDate());
   addIndexedAttribute(
       document, DefaultTaskSchema.getInstance().DATE_CREATION, task.getCreationDate());
   addIndexedAttribute(document, DefaultTaskSchema.getInstance().DATE_DUE, task.getDueDate());
   addIndexedAttribute(
       document, DefaultTaskSchema.getInstance().DATE_MODIFICATION, task.getModificationDate());
 }