code: public Integer getAndIncrementIDSeq(final String id) {
          Validate.notNull(id, "ID cannot be null");
          Integer count = this.idCounts.get(id);
          if (count == null) {
              count = Integer.valueOf(1);
          }
          this.idCounts.put(id, Integer.valueOf(count.intValue() + 1));
          return count;
      }
docs: <p>
  Returns a new index (ID count) for a specific
  value of the {@code id} attribute, and increments
  the count.
  </p>
  
  @param id the ID for which the count will be computed
  @return the new count, ready to be used