Method drain

examples/pulsar_processor_complex.rs:89–89

(&mut self, _buffer: VecDeque<ProcKafkaMessage>)

    async fn terminate(&mut self) {}

    async fn drain(&mut self, _buffer: VecDeque<ProcKafkaMessage>) {}

    async fn fill_buffer(&mut self, buffer_size: usize) -> Result<VecDeque<ProcKafkaMessage>, Terminate> {