title: LiveData observeForever not updating with the room changes
body: <p>following observeForever not giving any data when
      - User is logged out (There is no user in the database)
      - Login and insert a user into the db. (Here observeForever is not being triggered)</p>
  
  <pre><code>mUserDao.getCompleteUser().observeForever(this::updateCompleteUser);
  </code></pre>
  
  <p><strong>DAO</strong></p>
  
  <pre><code>@Dao
  public interface UserDao extends BaseDao&lt;User&gt; {
  @Query("SELECT * FROM user")
  @Transaction
  LiveData&lt;CompleteUser&gt; getCompleteUser();
  }
  </code></pre>
  
  <p>But <code>@Query("SELECT * FROM user")
       @Transaction
       Flowable&lt;CompleteUser&gt; getCompleteUser();</code></p>
  
  <p>is working which does not return null for the logged-out state (expected behavior)</p>
  
  <p><strong>User</strong></p>
  
  <pre><code>@Entity(tableName = "user")
  public class User implements Serializable {
  
      @PrimaryKey
      @NonNull
      String uid;
  
      String email;
  }
  </code></pre>
  
  <p><strong>Complete User</strong></p>
  
  <pre><code>public class CompleteUser {
      @Embedded
      User user;
  
      @Relation(parentColumn = "uid", entityColumn = "userId", entity = Address.class)
      List&lt;Address&gt; addresses;
  }
  </code></pre>