[The current test](https://github.com/google/guava/blob/acf29b389bc9ff8701f69d05b30e9d899bc10e35/guava-tests/test/com/google/common/base/SuppliersTest.java#L110) expects to get exceptions thrown again and again. But `Suppliers::memoize` is not called in the "testMemoizeExceptionThrown" test.

The line 115 should be replaced:

    private void memoizeExceptionThrownTest(ThrowingSupplier memoizedSupplier) {

To:

    private void memoizeExceptionThrownTest(ThrowingSupplier throwingSupplier) {
      Supplier<Integer> memoizedSupplier = Suppliers.memoize(throwingSupplier);
Supplier<Object> objectSupplier = Suppliers.ofInstance(toBeSupplied);
    assertSame(toBeSupplied, objectSupplier.get());
    assertSame(toBeSupplied, objectSupplier.get()); 
  }
  public void testOfInstanceSuppliesNull() {
    Supplier<Integer> nullSupplier = Suppliers.ofInstance(null);
    assertNull(nullSupplier.get());
  }
  @GwtIncompatible 
  public void testExpiringMemoizedSupplierThreadSafe() throws Throwable {
    Function<Supplier<Boolean>, Supplier<Boolean>> memoizer =
        new Function<Supplier<Boolean>, Supplier<Boolean>>() {
          @Override
          public Supplier<Boolean> apply(Supplier<Boolean> supplier) {
            return Suppliers.memoizeWithExpiration(supplier, Long.MAX_VALUE, TimeUnit.NANOSECONDS);
          }
        };
    testSupplierThreadSafe(memoizer);
  }
  @GwtIncompatible 
  public void testMemoizedSupplierThreadSafe() throws Throwable {
    Function<Supplier<Boolean>, Supplier<Boolean>> memoizer =
        new Function<Supplier<Boolean>, Supplier<Boolean>>() {
          @Override
          public Supplier<Boolean> apply(Supplier<Boolean> supplier) {
            return Suppliers.memoize(supplier);
          }
        };
    testSupplierThreadSafe(memoizer);
  }