code: public synchronized void neverGeneratePID(String pid) throws IOException {
          logger.debug("Never generating PID: {}", pid);
          try {
              PID p = new PID(pid);
              String ns = p.getNamespaceId();
              int id = Integer.parseInt(p.getObjectId());
              if (id > getHighestID(ns)) {
                  setHighestID(ns, id);
              }
          } catch (MalformedPIDException mpe) {
              throw new IOException(mpe.getMessage());
          } catch (NumberFormatException nfe) {
              // if the id part is not numeric, we already know we'll
              // never generate that id because all generated ids are numeric.
          }
      }
docs: Cause the given PID to never be generated by the PID generator.