Motivation:
RedisEncoderTest did not release all buffers correctly which could lead to leaks.
Modifications:
Call ByteBuf.release() after buffer is read.
Result:
No more leaks in RedisEncoderTest.
Motivation:
- `RedisBulkStringAggregator` raises errors for multiple null bulk strings.
- Null or empty bulk string has no content, but current `RedisDecoder` generates header and contents.
Modifications:
- Fix decoding null bulk string of `RedisDecoder` for `RedisBulkStringAggregator`.
Result:
- Fixes#5184.
