builder.add(counter.getAndIncrement());
      }
    },
    ADD_ARRAY {
      @Override
      void doIt(ImmutableIntArray.Builder builder, AtomicInteger counter) {
        int[] array = new int[RANDOM.nextInt(10)];
        for (int i = 0; i < array.length; i++) {
          array[i] = counter.getAndIncrement();
        }
        builder.addAll(array);
      }
    },

        builder.add(counter.getAndIncrement());
      }
    },
    ADD_ARRAY {
      @Override
      void doIt(ImmutableDoubleArray.Builder builder, AtomicInteger counter) {
        double[] array = new double[RANDOM.nextInt(10)];
        for (int i = 0; i < array.length; i++) {
          array[i] = counter.getAndIncrement();
        }
        builder.addAll(array);
      }
    },

        builder.add(counter.getAndIncrement());
      }
    },
    ADD_ARRAY {
      @Override
      void doIt(ImmutableDoubleArray.Builder builder, AtomicInteger counter) {
        double[] array = new double[RANDOM.nextInt(10)];
        for (int i = 0; i < array.length; i++) {
          array[i] = counter.getAndIncrement();
        }
        builder.addAll(array);
      }
    },

        static final AtomicInteger THREAD_NUMBER = new AtomicInteger(1);

        public Thread newThread(Runnable r) {
            Thread newThread = new Thread(GROUP, r, "resolver-" + THREAD_NUMBER.getAndIncrement());
            newThread.setDaemon(true);
            newThread.setContextClassLoader(null);
            return newThread;
        }
    }

    private class ResolveTask implements Runnable {

        // One or more integer values could be skipped in the event of a race
        // to generate a UID for the same object from multiple threads, but
        // that shouldn't be a problem.
        uid = counter.getAndIncrement();
        Integer alreadySet = uids.putIfAbsent(obj, uid);
        if (alreadySet != null) {
          uid = alreadySet;
        }
      }
      return uid;
    }

    @Override

        // One or more integer values could be skipped in the event of a race
        // to generate a UID for the same object from multiple threads, but
        // that shouldn't be a problem.
        uid = counter.getAndIncrement();
        Integer alreadySet = uids.putIfAbsent(obj, uid);
        if (alreadySet != null) {
          uid = alreadySet;
        }
      }
      return uid;
    }

    @Override