AbstractIterator<Integer> empty =
        new AbstractIterator<Integer>() {
          private boolean alreadyCalledEndOfData;

          @Override
          public @Nullable Integer computeNext() {
            if (alreadyCalledEndOfData) {
              fail("Should not have been invoked again");
            }
            alreadyCalledEndOfData = true;
            return endOfData();
          }
        };

    try {

    AbstractIterator<Integer> empty =
        new AbstractIterator<Integer>() {
          private boolean alreadyCalledEndOfData;

          @Override
          public @Nullable Integer computeNext() {
            if (alreadyCalledEndOfData) {
              fail("Should not have been invoked again");
            }
            alreadyCalledEndOfData = true;
            return endOfData();
          }
        };

    try {

    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          boolean haveBeenCalled;

          @Override
          public Integer computeNext() {
            if (haveBeenCalled) {
              throw new AssertionError("Should not have been called again");
            } else {
              haveBeenCalled = true;
              sneakyThrow(new SomeCheckedException());

    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          boolean haveBeenCalled;

          @Override
          public Integer computeNext() {
            if (haveBeenCalled) {
              throw new AssertionError("Should not have been called again");
            } else {
              haveBeenCalled = true;
              sneakyThrow(new SomeCheckedException());