*
     * - _shouldn't_ be null, so we don't annotate it with @Nullable
     *
     * - _can_ be null without causing a runtime failure (because we don't want the interesting
     *   details of precondition failure to be hidden by an exception we throw about an unexpectedly
     *   null _failure message_)
     *
     * That combination upsets NullPointerTester, which wants any call that passes null for a

     * @param closingExecutor the object will be closed on this executor
     * @return the first argument
     */
    @CanIgnoreReturnValue
    @ParametricNullness
    // TODO(b/163345357): Widen bound to AutoCloseable once we require API Level 19.
    public <C extends @Nullable Object & @Nullable Closeable> C eventuallyClose(
        @ParametricNullness C closeable, Executor closingExecutor) {