* Added dotnet 7 support/builds.

* Added NETCOREAPP_3_1_OR_GREATER where applicable.

* Expose TCP keep alive options to options builder

* Update ReleaseNotes.md

* Expose more options in disconnect options.

* Expose more options in disconnect API.

* Refactor code.

* Expose user properties in disconnected event.

* Expose more disconnect options in server.

* Fix build errors

* Add new samples.

* Fix client cleanup

* Fix merge conflicts

* Add feature validation.

* Update ReleaseNotes.md

* Add validators or subscribe and unsubscribe.

* Add feature validation for disconnect.

* Fix build errors.

* Fix build errors
Co-authored-by: NHansM <HansM2013@gmx.de>

* performance optimization of SendPacketAsync

* Update Source/MQTTnet.AspnetCore/MqttConnectionContext.cs
Co-authored-by: NGünther Foidl <gue@korporal.at>
Co-authored-by: NGünther Foidl <gue@korporal.at>

Bumps [Newtonsoft.Json](https://github.com/JamesNK/Newtonsoft.Json) from 13.0.1 to 13.0.2.
- [Release notes](https://github.com/JamesNK/Newtonsoft.Json/releases)
- [Commits](https://github.com/JamesNK/Newtonsoft.Json/compare/13.0.1...13.0.2)

---
updated-dependencies:
- dependency-name: Newtonsoft.Json
  dependency-type: direct:production
...
Signed-off-by: Ndependabot[bot] <support@github.com>
Signed-off-by: Ndependabot[bot] <support@github.com>
Co-authored-by: Ndependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Adapting mqtt over tcp.

Avoid a split MqttPacketBuffer transfer caused by triggering PipeWriter.FlushAsync twice.

* Avoid copying buffer from ReadOnlySequence as  ReceivedMqttPacket body

* Use ReadOnlySequence.FirstSpan if possible.

* add ReaderExtensionsBenchmark

* update benchmark

* fix fixedHeader incorrect read
Co-authored-by: NChristian <6939810+chkr1011@users.noreply.github.com>

use Memory-Copy
Co-authored-by: NChristian <6939810+chkr1011@users.noreply.github.com>

Refactor code of MqttBufferWriter

* Avoid to call MqttPacketBuffer.Join() when SendPacketAsync

* Safely cleanup the PacketFormatterAdapter

* Keep buffer.Join when mqtt over webSocket

* null checking for IHttpContextFeature.HttpContext