private static void assertResponseTimeoutExceptionOrDeadlineExceeded(@Nullable Throwable cause) {
        assertThat(cause).isNotNull();

        // Both exceptions can be raised when a timeout occurs due to timing issues,
        // and the first triggered one wins.
        if (cause instanceof ResponseTimeoutException) {
            return;
        }
        if (cause instanceof StatusRuntimeException) {
            assertThat(((StatusRuntimeException) cause).getStatus().getCode())
                    .isEqualTo(Code.DEADLINE_EXCEEDED);
            return;
        }
        fail("cause must be a ResponseTimeoutException or a StatusRuntimeException: ", cause);
    }
Must be at least {@link #unaryPayloadLength()}, plus some to account for encoding overhead.
grpc/src/test/java/com/linecorp/armeria/client/grpc/GrpcClientTest.java