code: @SuppressWarnings("ReturnOfNull")
      public static <T> T throwUnsafely(Throwable cause) {
          doThrowUnsafely(requireNonNull(cause, "cause"));
          return null; // Never reaches here.
      }
docs: Throws the specified exception violating the {@code throws} clause of the enclosing method.
  This method is useful when you need to rethrow a checked exception in {@link Function}, {@link Consumer},
  {@link Supplier} and {@link Runnable}, only if you are sure that the rethrown exception will be handled
  as a {@link Throwable} or an {@link Exception}. For example:
  <pre>{@code
  CompletableFuture.supplyAsync(() -> {
  try (FileInputStream fin = new FileInputStream(...)) {
  ....
  return someValue;
  } catch (IOException e) {
  // 'throw e;' won't work because Runnable.run() does not allow any checked exceptions.
  return Exceptions.throwUnsafely(e);
  }
  }).exceptionally(CompletionActions::log);
  }</pre>
  
  @return This method never returns because it always throws an exception. However, combined with an
  arbitrary return clause, you can terminate any non-void function with a single statement.
  e.g. {@code return Exceptions.throwUnsafely(...);} vs.
  {@code Exceptions.throwUnsafely(...); return null;}