RuntimeException re = new RuntimeException(iae);
    IllegalStateException ex = new IllegalStateException(re);

    assertThat(getCausalChain(ex)).containsExactly(ex, re, iae, sue).inOrder();
    assertSame(sue, Iterables.getOnlyElement(getCausalChain(sue)));

    List<Throwable> causes = getCausalChain(ex);
    assertThrows(UnsupportedOperationException.class, () -> causes.add(new RuntimeException()));
  }

    RuntimeException re = new RuntimeException(iae);
    IllegalStateException ex = new IllegalStateException(re);

    assertThat(getCausalChain(ex)).containsExactly(ex, re, iae, sue).inOrder();
    assertSame(sue, Iterables.getOnlyElement(getCausalChain(sue)));

    List<Throwable> causes = getCausalChain(ex);
    assertThrows(UnsupportedOperationException.class, () -> causes.add(new RuntimeException()));
  }

   * <pre>
   * Iterables.filter(Throwables.getCausalChain(e), IOException.class));
   * </pre>
   *
   * @param throwable the non-null {@code Throwable} to extract causes from
   * @return an unmodifiable list containing the cause chain starting with {@code throwable}
   * @throws IllegalArgumentException if there is a loop in the causal chain
   */
  public static List<Throwable> getCausalChain(Throwable throwable) {