'System.Text.Json.ReflectionMemberAccessor' could not be found

[myokeeh]

Describe the bug

Projects updated to latest 7.0.2 version now building with this warning:

Embedded manifest in Microsoft.Toolkit.Uwp.UI.Controls.Media: Microsoft.Toolkit.Uwp.UI.Controls.Media.Properties.Microsoft.Toolkit.Uwp.UI.Controls.rd.xml(5): warning : ILTransform : warning ILT0027: Type 'System.Text.Json.ReflectionMemberAccessor' could not be found.

Not seen on version 7.0.0 or 7.0.1

Steps to Reproduce

Steps to reproduce the behavior:

1. Update to 7.0.2

Environment

NuGet Package(s):  7.0.2

Package Version(s): 

Windows 10 Build Number:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [ ] May 2020 Update (19041)
- [x] Insider Build (build number: 19043)

App min and target version:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [x] May 2020 Update (19041)
- [x] Insider Build (19043)

Device form factor:
- [x] Desktop
- [ ] Xbox
- [ ] Surface Hub
- [ ] IoT

Visual Studio 
- [ ] 2017 (version: )
- [x] 2019 (version: 16.9.5) 
- [ ] 2019 Preview (version: )

Hello myokeeh, thank you for opening an issue with us!

I have automatically added a "needs triage" label to help get things started. Our team will analyze and investigate the issue, and escalate it to the relevant team if possible. Other community members may also look into the issue and provide feedback 🙌

[Kyaa-dost]

@myokeeh can you try recreating your project? Also, please specify the steps you are taking from the beginning.

[michael-hawker]

@azchohfi I had moved the System.Text.Json version up in our last patch here: f08a351

I didn't notice any issues in the smoke tests or our unit tests around this. Thoughts?

[azchohfi]

That file has changed, and, in theory, to fix the issue we were working around with out rd.xml file:
dotnet/runtime@c73ef49#diff-f5720afdbbfb4d6676f9ae0daad63b3ddd84a818803f00c2566cdc4c9f5a0ac3
Maybe we just don't need that line anymore? Not that it matters much, but the rd.xml files do not seem to match the project name, so it took me a while to figure that this was the media one. I would open a separate issue to rename these files to match their projects.

[myokeeh]

@Kyaa-dost, do you still need more info given the last two comments?

[michael-hawker]

@myokeeh I've tried removing the line that @azchohfi tested here: #4037

When it builds it should provide a NuGet package you can try by following our preview package steps in our wiki here - would you mind trying that out and seeing if it resolves your issue? (If you can check your project runs in Release as well, that'd be great.)

Edit: Should be 7.0.0-build.1191+253df42f96

[Nirmal4G]

@azchohfi

I would open a separate issue to rename these files to match their projects.

I also did hit a different issue that prompted me to check and rename these files to match the library name. The changes are already in my PR #3893.