change from Memory to ReadOnlyMemory

[bollhals]

Proposed Changes

Aligns the type to the usage (None of them actually should modify the memory, as we're sending it, hence it should be read only.) Also the usage of
MemoryMarshal.TryGetArray<T>(ReadOnlyMemory<T>, ArraySegment<T>)
requires a ReadOnlyMemory not Memory.

Types of Changes

• Bug fix (non-breaking change which fixes issue #NNNN)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause an observable behavior change in existing systems)
• Documentation improvements (corrections, new content, etc)
• Cosmetic change (whitespace, formatting, etc)

Checklist

• I have read the CONTRIBUTING.md document
• I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)
• All tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in related repositories

[michaelklishin]

Thank you!

[michaelklishin]

@bollhals this can be a candidate for backporting to 6.x. WDYT?

[bollhals]

Yes this could be backported, but there's not much gain from it either. It's more consistency than anything else really.

[michaelklishin]

OK