title: Hibernate Criteria with group by getting error
body: <p>I have these two Entity java class which is referring the tables (jos_content &amp; jos_article_section).</p>
  
  <pre><code>@Entity
  @Table(name="jos_content", 
  uniqueConstraints={@UniqueConstraint(columnNames="id")})
  public class ContentEntity implements Serializable {
  private int id; 
  private Set&lt;ArticleSectionEntity&gt; josArticleSection;    
  private String sefUrl;
  
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  @Column(name="id", unique = true, nullable = false)
  public int getId() {
      return id;
  }   
  public void setId(int id) {
      this.id = id;
  }
  
  @Column(name="sef_url")
  public String getSefUrl() {
      return sefUrl;
  }
  public void setSefUrl(String sefUrl) {
      this.sefUrl = sefUrl;
  }
  
  @OneToMany(cascade = CascadeType.ALL)
  @JoinColumn(name="article_id")
  public Set&lt;ArticleSectionEntity&gt; getJosArticleSection() {
      return josArticleSection;
  }
  public void setJosArticleSection(Set&lt;ArticleSectionEntity&gt; josArticleSection) {
      this.josArticleSection = josArticleSection;
  }
  }
  
  
  @Entity
  @Table(name="jos_article_section", uniqueConstraints=    {@UniqueConstraint(columnNames="id")})
  public class ArticleSectionEntity implements Serializable {
  private int id; 
  private int articleId;
  
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  @Column(name="id", nullable=false, length=10)
  public int getId() {
      return id;
  }
  public void setId(int id) {
      this.id = id;
  }
  
  @Column(name="article_id", nullable=false)
  public int getArticleId() {
      return articleId;
  }
  }
  </code></pre>
  
  <p>I'm using Criteria interface with group by like this:</p>
  
  <pre><code>Criteria contentCriteria = session.createCriteria(ContentEntity.class, "content");
  // Join two tables (jos_content, jos_article_section) on  jos_content.id =     jos_acticle_section.article_id
  contentCriteria = contentCriteria.setFetchMode("josArticleSection", FetchMode.JOIN);
  contentCriteria = contentCriteria.add(Restrictions.eq("content.id", storyId));
  contentCriteria = contentCriteria.add(Restrictions.eq("content.state",1));          
  
  //Start Group By Clause
  PropertyProjection propProjection = Projections.groupProperty("content.id");
  contentCriteria = contentCriteria.setProjection(propProjection);
  //End Group By
  </code></pre>
  
  <p>When I running my application, i'm getting this output with error as:</p>
  
  <pre><code>contentCriteria &gt;&gt;&gt;&gt; CriteriaImpl(com.itgd.entity.ContentEntity:content[][content.id=374821, content.state=1]content.id)
  14:24:39,649 INFO  [STDOUT] Hibernate: select this_.id as y0_ from jos_content this_  where this_.id=? and this_.state=? group by this_.id
  14:24:39,659 ERROR [STDERR] java.lang.ClassCastException: java.lang.Integer cannot be cast to com.itgd.entity.ContentEntity
  </code></pre>
  
  <p>How do I have to resolve this error and is it possible to keep all the fields with group by, using Criteria interface?
  Please let know, if anyone guide me.</p>