title: One-to-Many relationship mapping returns validation errors
body: <p>Edited with the new situation per suggestion in the comments:</p>
  <p>Currently I have this mapping</p>
  <pre><code>public ShowMap() {
          ToTable(&quot;Shows&quot;);
          HasKey(x =&gt; x.ShowID);
  
          Property(x =&gt; x.ShowID)
              .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity)
              .IsRequired()
              .HasColumnName(&quot;ShowID&quot;);
  }
  
  public EpisodeMap() {
          ToTable(&quot;Episodes&quot;);
          HasKey(x =&gt; x.EpisodeID);
  
          Property(x =&gt; x.EpisodeID)
          .IsRequired()
          .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity)
          .HasColumnName(&quot;EpisodeID&quot;);
  
          Property(x =&gt; x.ShowID)
              .IsRequired()
              .HasColumnName(&quot;ShowID&quot;);
  
          Property(x =&gt; x.EpisodeNumber)
              .IsRequired()
              .HasColumnName(&quot;EpisodeNumber&quot;);
  }
  </code></pre>
  <p>This results in the following database:</p>
  <p><img src="https://i.stack.imgur.com/ak4I8.png" alt="Episodes" /></p>
  <p><img src="https://i.stack.imgur.com/MGVgD.png" alt="Shows" /></p>
  <p>However, when the seed method is run I receive this error. Since I can't debug the value of variables from the command line command <code>Update-Database</code> (at least, not as far as I know) I can't see what the property holds.</p>
  <blockquote>
  <p>Validation failed for one or more entities. See 'EntityValidationErrors' property for more details.</p>
  </blockquote>
  <p>When I add the relationship to the mapping, I receive the following error:</p>
  <blockquote>
  <p>One or more validation errors were detected during model generation:</p>
  <p>System.Data.Entity.Edm.EdmAssociationEnd: : Multiplicity is not valid in Role 'Episode_Show_Source' in relationship 'Episode_Show'. Because the Dependent Role refers to the key properties, the upper bound of the multiplicity of the Dependent Role must be '1'.</p>
  </blockquote>
  <p>Relationship:</p>
  <pre><code>        HasRequired(x =&gt; x.Show)
              .WithMany(x =&gt; x.Episodes)
              .HasForeignKey(x =&gt; x.EpisodeID);
  </code></pre>
  <p>This is the model:</p>
  <pre><code>public class Episode {
    public int EpisodeID {get; set;}
    public int ShowID {get; set;}
    public int EpisodeNumber {get; set;}
    public virtual Show Show { get; set; }
  }
  
  public class Show {
    public int ShowID {get; set;}
    public virtual ICollection&lt;Episode&gt; Episodes { get; set; }
  }
  </code></pre>
  <p>What have I overlooked that causes validation errors?</p>
  <p>Edit: just to be certain I haven't forgotten anything, <a href="https://github.com/Vannevelj/NoName/tree/master/NoName/NoName" rel="noreferrer">this</a> is the project on github.</p>