Get ALL references that can be found in the current Assembly, excluding own references (takes ~400ms on 34 .NET (core) references)

GetAllReferences.cs

/// <summary>
/// Load all references/namespaces that can be found in this assembly (excluding own references)
/// </summary>
public static string[] LoadReferences()
{
    //Get all namespaces from this assembly (own project, own library, ..)
    IEnumerable<string> ownNamespaces = Assembly.GetExecutingAssembly().GetTypes()
        .Select(t => t.Namespace)
        .Distinct();

    List<string> allNamespaces = new List<string>();
    
    //Get all .NET defined types
    IEnumerable<Type[]> types = AppDomain.CurrentDomain
        .GetAssemblies()
        .Where(a => Assembly.GetCallingAssembly().GetReferencedAssemblies().Select(ra => ra.FullName).Contains(a.FullName))
        .Select(a => a.GetExportedTypes());
    
    //Add all types where namespace is not own namespace (no own references)
    foreach (Type[] type in types)
    {
        allNamespaces.AddRange(type
            .Select(t => t.Namespace)
            .Where(n => n != null && !ownNamespaces.Contains(n))
            .Distinct());
    }

    return allNamespaces.ToArray();
}