code: private static ImmutableList<String> immutableCopy(List<String> tags) {
          if (tags == null
                  || tags.size() == 0
                  || (tags.size() == 1 && tags.get(0) == null)) {
              return ImmutableList.of();
          }
  
          return ImmutableList.copyOf(tags);
      }
docs: Creates an immutable list of tags, taking into account jOOQ's peculiar
  mapping of an empty postgres array to a one-element list whose only
  element is {@code null}.
  
  @param tags the list of tags
  @return an immutable copy of tags.