Sometimes ProjectStartedEventArgs doesn't contain Properties/Items

[KirillOsenkov]

In some .binlogs for some projects for some initial targets we see Properties/Items missing from under the project node. We think it's most likely in MSBuild.

All the BinaryLogger does is this:
https://source.dot.net/#Microsoft.Build/Logging/BinaryLogger/BuildEventArgsWriter.cs,179

Basically under some circumstances ProjectStartedEventArgs.Properties may be null.

[cdmihai]

So apparently, initial properties and items do not appear on parallel builds that contain projects with errors or projects that get skipped. It's the same behaviour with dev14. But they appear in sequential builds, so at least there's a workaround. Here's a repro:
play.zip

Wonder if this is it, or if there are other situations too. I'll start investigating this repro.

[KirillOsenkov]

There are two reasons that the project started args would differ:

The first is that by default we do not log properties/items if the build is running on a remote node: https://github.com/microsoft/msbuild/blob/master/src/Build/BackEnd/Components/Logging/ProjectLoggingContext.cs#L88. this accounts for almost all of the diff you might see.

The second is that if the system finds the result of a build in the cache, here: https://github.com/microsoft/msbuild/blob/master/src/Build/BackEnd/Components/Logging/NodeLoggingContext.cs#L83, then the properties and items have not be rehydrated and will not be present