code: public void setFormatters(Formatter<?>[] formatters) {
          if (formatters != null && formatters.length > 0) {
              for (Formatter<?> formatter : formatters) {
                  if (formatter != null) {
                      Class<?> type = ClassUtils.getGenericClass(formatter.getClass());
                      if (type != null) {
                          this.formatters.put(type, formatter);
                      }
                  }
              }
              Map<Class<?>, Formatter<?>> sorted = new TreeMap<Class<?>, Formatter<?>>(ClassComparator.COMPARATOR);
              sorted.putAll(this.formatters);
              this.sortedFormatters = Collections.unmodifiableMap(sorted);
          }
      }
docs: httl.properties: formatters+=httl.spi.formatters.NumberFormatter