fix: convert session_present flag to boolean to follow the declared type

[SergeTupchiy]

No description provided.

[SergeTupchiy]

NOTE: it will break a few tests in emqx.

[SergeTupchiy]

Alternatively, can be fixed in https://github.com/emqx/emqtt/blob/fix-session_present-type/src/emqtt_frame.erl#L218
similarly to how CONNECT packet flags are parsed to bools: https://github.com/emqx/emqtt/blob/fix-session_present-type/src/emqtt_frame.erl#L202

But it would require changing the record field, e.g:

#mqtt_packet_connack{session_present  = SessionPresent,

Instead of:

#mqtt_packet_connack{ack_flags   = AckFlags,

[qzhuyan]

I think it is a good change but may break many places, worth it?
Do you have a good reason?

[SergeTupchiy]

I think it is a good change but may break many places, worth it? Do you have a good reason?

No reason, besides improving consistency (other flags are converted and stored as boolean).
In emqx session_present flag is only used in a few test cases which would be easy to fix.

Instead of this fix, we may change type of session_present to integer: https://github.com/emqx/emqtt/blob/master/src/emqtt.erl#L252 ?

[thalesmg]

I think it is a good change but may break many places, worth it? Do you have a good reason?

No reason, besides improving consistency (other flags are converted and stored as boolean). In emqx session_present flag is only used in a few test cases which would be easy to fix.

Instead of this fix, we may change type of session_present to integer: https://github.com/emqx/emqtt/blob/master/src/emqtt.erl#L252 ?

IMO, using a boolean is more semantic for this case. Maybe we could indicate this is a breaking change with a major version bump?