Validating references in custom assembly definition

Hi,

I've created some custom assembly definitions for our project, and they have various references to other assemblies (Unity packages, other plugins, &c). I'm writing some editor scripts just to verify that our main assembly – call it MyGame.asmdef – has valid references listed. For instance, for testing purposes, I created a placeholder assembly, added it to MyGame.asmdef's references, then deleted the assembly from disk; now the inspector shows simply

None (Assembly Definition Asset)

in the inspector field for that reference.

So far, I've written some quick code just to get a handle on all references in the project:

Code (CSharp):

1. var assemblies = CompilationPipeline.GetAssemblies();
2. for (int i=0; i < assemblies.Length; ++i) {
3.     var refs = assemblies[i].assemblyReferences;
4.     foreach (var reference in refs) {
5.         Debug.Log("i am " + assemblies[i].name + " and i ref " + reference.outputPath);
6.     }
7. }

In my test example however, the output is

i am MyGame and i ref Library/ScriptAssemblies/UnityEngine.UI.dll

I'm not totally sure why it lists a reference to UnityEngine.UI – was it auto-populated when I deleted the placeholder assembly? if so, why wasn't the inspector updated?

Is there a better way to validate all the references in a given assembly?