threads[i] =
          new Thread() {
            @Override
            public void run() {
              for (int j = 0; j < iterations; j++) {
                Object unused = Suppliers.synchronizedSupplier(nonThreadSafe).get();
              }
            }
          };
    }
    for (Thread t : threads) {
      t.start();
    }
    for (Thread t : threads) {
      t.join();
    }

      threads[i] =
          new Thread() {
            @Override
            public void run() {
              for (int j = 0; j < iterations; j++) {
                Object unused = Suppliers.synchronizedSupplier(nonThreadSafe).get();
              }
            }
          };
    }
    for (Thread t : threads) {
      t.start();
    }
    for (Thread t : threads) {
      t.join();
    }