code: public static void propagateIfPossible(Throwable throwable) {
      if (throwable != null) {
        com.google.common.base.Throwables.throwIfUnchecked(throwable);
      }
    }
docs: Propagates {@code throwable} exactly as-is, if and only if it is an instance of {@link
  RuntimeException} or {@link Error}. Example usage:
  
  <pre>
  try {
  someMethodThatCouldThrowAnything();
  } catch (IKnowWhatToDoWithThisException e) {
  handle(e);
  } catch (Throwable t) {
  Throwables.propagateIfPossible(t);
  throw new RuntimeException("unexpected", t);
  }
  </pre>
  
  @param throwable throwable (may be {@code null})