void awaitAbort(@Nullable Throwable cause) {
            if (cause == null) {
                assertThatThrownBy(() -> publisher.whenComplete().join())
                        .hasCauseInstanceOf(AbortedStreamException.class);
            } else {
                assertThatThrownBy(() -> publisher.whenComplete().join())
                        .hasCauseInstanceOf(cause.getClass());
            }
        }
Tests if {@link PublisherBasedStreamMessage#abort()} prohibits further subscription.
core/src/test/java/com/linecorp/armeria/common/stream/PublisherBasedStreamMessageTest.java