title: Room persistent database - how to insert list of items into DB when it has no primary key related to table
body: <p>I am having a hard time getting a list item into room. the list item is called measurements and its of type Measurement.  the list item has no primarykey that would be related to the database.
  but i have no problem adding the same primary key for the ProductModel if necessary.  </p>
  
  <p>Here is what i have so far: </p>
  
  <pre><code>@Entity(tableName = TABLE_NAME)
  public class ProductModel {
  
      public static final String TABLE_NAME = "product";
  
      @PrimaryKey
      private int idProduct;
  
      private int idCategoryDefault;
  
      @Relation(parentColumn = "idProduct", entityColumn = "idProduct", entity = SortedAttribute.class)
      private List&lt;SortedAttribute&gt; sortedAttributes = null;
  }
  
  @Entity
  public class SortedAttribute {
  
      @PrimaryKey
      private int idProduct;
  
      private String reference;
  
      @Embedded
      private List&lt;Measurement&gt; measurements = null; //****how do i get this into room ? its a LIST of measurements, not a measurement so calling Embedded i think wont work as it cant flatten it****/
  }
  
  public class Measurement {
  
      private String value;
      private String valueCm;
  
      public Measurement() {
      }
  }
  </code></pre>