Re-review use of Task vs ValueTask in API

[lukebakken]

See the discussion here: #1642

cc @danielmarbach

[lukebakken]

@danielmarbach @stebet @paulomorgado @Hawxy

Re: Task vs ValueTask in the public API - my current inclination is to just use Task unless someone can come up with a concrete benchmark showing an appreciable performance benefit for ValueTask, or provide another compelling reason to use ValueTask.

As you are all aware, version 7 has been years in the making. I am going to ship version 7 this month, no matter what 😸

[danielmarbach]

I definitely don't want to derail the release @lukebakken

Just sharing thoughts and observations from our upgrade attempts. At the end of the day, if we leave things as is, that's also fine.

[lukebakken]

Just sharing thoughts and observations from our upgrade attempts.

I'm all for making migrations from 6.x easier.

[danielmarbach]

Well one of the biggest pain points was that the order of some parameters changed and not the value task vs task 😜

[lukebakken]

Well one of the biggest pain points was that the order of some parameters changed

I'm planning to update the tutorials to use the latest RC before shipping version 7, so I'll probably make note of this, but if you'd like to mention which changes were most annoying that would be great. Maybe I can restore the parameter order in the API.

[danielmarbach]

@lukebakken the entire diff is visible here Particular/NServiceBus.RabbitMQ#1446

[lukebakken]

@danielmarbach it looks like the BasicPublishAsync API was the biggest (maybe only?) offender, so I reverted the parameter order change in this commit: 5abd912

[lukebakken]

Based on the comment by @Hawxy -

#1413 (comment)

...I re-visited IChannel. Those methods that directly call ModelSendAsync without an RPC continuation will return ValueTask, while everything else returns Task or Task<>. Thanks everyone.