title: Property not being ignored in EntityTypeConfiguration?
body: <p>I have a simple entity class with a list of base classes, which is ignored in the model:</p>
  <pre><code>public class MyClass
  {
      public int Id {get;set;}
      public List&lt;BaseChild&gt; BaseChildren {get; set;}
  }
  
  </code></pre>
  <p>Which has this configuration:</p>
  <pre><code>public class MyClassConfiguration : IEntityTypeConfiguration&lt;MyClass&gt;
  {
      public void Configure(EntityTypeBuilder&lt;MyClass&gt; builder)
      {
          builder.Property(o =&gt; o.Id).UseHiLo();
          builder.HasKey(o =&gt; o.Id);
      
          builder.Ignore(o =&gt; o.BaseChildren);
      }
  }
  </code></pre>
  <p>I have classes that inherit from BaseChild and they all use this configuration:</p>
  <pre><code>public abstract class BaseChild
  {
      public int MyClassId { get; set; }
  }
  
  public abstract class BaseChildConfiguration&lt;T&gt; : IEntityTypeConfiguration&lt;T&gt; where T : BaseChild
  {
      public virtual void Configure(EntityTypeBuilder&lt;T&gt; builder)
      {
          builder.HasKey(o =&gt; o.MyClassId);
          builder.HasOne&lt;MyClass&gt;()
              .WithOne()
              .HasForeignKey&lt;T&gt;(o =&gt; o.MyClassId);
      }
  }
  
  </code></pre>
  <pre><code>public class Instance : Component
  {
      public long Code { get; set; }
  }
  
  public class InstanceConfiguration : BaseChildConfiguration&lt;Instance&gt;
  {
  }
  
  </code></pre>
  <p>All the configurations are properly being applied in my OnModelCreating:</p>
  <pre><code>protected override void OnModelCreating(ModelBuilder mb)
  {
      mb.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());
  }
  
  </code></pre>
  <p>Yet for some reason I keep getting the following exception:</p>
  <blockquote>
  <p>A key cannot be configured on 'Instance' because it is a derived type. The key must be configured on the root type 'BaseChild'. If you did not intend for 'BaseChild' to be included in the model, ensure that it is not included in a DbSet property on your context, referenced in a configuration call to ModelBuilder, or referenced from a navigation property on a type that is included in the model.</p>
  </blockquote>