Problème de requête avec JPA

SELECT e FROM Employe e WHERE e.groupes.numeroGroupe=:x 

e.groupes.numeroGroupe=:x

Employe e = ...
Collection<Groupe> g = e.groupes;
Long n = g.numeroGroupe; // Erreur : g est une Collection, pas un Group !!

Caused by: java.lang.NumberFormatException: For input string: "numeroGroupe"
 at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
 at java.lang.Integer.parseInt(Integer.java:580)
 at java.lang.Integer.parseInt(Integer.java:615)
 at javax.el.ListELResolver.toInteger(ListELResolver.java:409)
 at javax.el.ListELResolver.getValue(ListELResolver.java:202)
 at org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:110)
 at com.sun.el.parser.AstValue.getValue(AstValue.java:139)
 at com.sun.el.parser.AstValue.getValue(AstValue.java:203)
 at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:226)
 at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:917)
 at org.apache.jsp.assets.gestionnaire.employesParGroupe_jsp._jspx_meth_c_005fforEach_005f0(employesParGroupe_jsp.java:828)
 at org.apache.jsp.assets.gestionnaire.employesParGroupe_jsp._jspService(employesParGroupe_jsp.java:616)
 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
 at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:433)
 ... 44 more

<div class="form-group">
                  <label for="exampleInputPassword1">Saisir le code du groupe</label>
                  <input type="number" class="form-control" name="codeGroupe"  id="exampleInputPassword1" placeholder="Code du groupe" required="required">
                </div>

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


  String codeGr=request.getParameter("codeGroupe");
  try {
   Long cGr=Long.parseLong(codeGr);

   DaoImpl d=new DaoImpl();
   List<Employe> listeEmployes=new ArrayList<Employe>();
      listeEmployes=d.employesParGroupe(cGr);
     request.setAttribute("liste", listeEmployes);
   request.getRequestDispatcher("employesParGroupe.jsp").forward(request, response);
   
   
  } catch (NumberFormatException e) {
   System.out.println("n'est pas un nombre");
  }
  
 
 }

              <table id="example2" class="table table-bordered table-hover">
                <thead>
                <tr>
                
                  <th>Groupe</th>
                  <th>Employe</th>
                                    
                </tr>
                </thead>
                    <tbody>
                              <c:forEach items="${requestScope.liste }" var="emp">
                   
                                           <tr>
                                                <td>${emp.groupes.numeroGroupe}</td>
                                           
                                            <td>${emp.codeEmploye}</td>

                                            </tr>
                               </c:forEach>
                                        </tbody> 
               <tfoot>
                                          <tr>
                                    
                  <th>Groupe</th>
                  <th>Employe</th>
                                    
                  
                </tr>
                                        </tfoot>
              </table>
            </div>
            <!-- /.box-body -->
          </div>

@Entity 
@Table(name="EMPLOYE") 
public class Employe implements Serializable{ 
@Id 
@GeneratedValue(strategy=GenerationType.IDENTITY) 
@Column(name="CODE_EMPLOYE") 
private Long codeEmploye; 

@ManyToMany 
@JoinTable(name="EMPLOYE_GROUPE", 
joinColumns=@JoinColumn(name="CODE_EMPLOYE"), 
inverseJoinColumns=@JoinColumn(name="NUMERO_GROUPE") 

) 
private Collection<Groupe> groupes; 
} 
@Entity 
@Table(name="GROUPE") 
public class Groupe implements Serializable{ 
@Id 
@GeneratedValue(strategy=GenerationType.IDENTITY) 
@Column(name="NUMERO_GROUPE") 
private Long numeroGroupe; 
@OneToMany(mappedBy="groupes") 
private Collection<Employe> employes; 
}

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