code: public String csvIdentifiers(Set<Identifier> ids) {
          if (ids == null || ids.isEmpty()) {
              return "\"\"";
          }
          boolean addComma = false;
          final StringBuilder sb = new StringBuilder();
          for (Identifier id : ids) {
              if (addComma) {
                  sb.append(", ");
              } else {
                  addComma = true;
              }
              sb.append(id.getValue());
          }
          if (sb.length() == 0) {
              return "\"\"";
          }
          return StringEscapeUtils.escapeCsv(sb.toString());
      }
docs: Takes a set of Identifiers, filters them to none CPE, and formats them
  for display in a CSV.
  
  @param ids the set of identifiers
  @return the formatted list of none CPE identifiers