title: NullValueInNestedPathException for Bean[] class binding
body: <p>Hello I'd like to ask if you can assign arrays of beans as a form</p>
  
  <p>for example i have a form:</p>
  
  <pre><code> PageForm{
     Group[] groupArray;
  
     Group[] getGroupArray(){
        return groupArray;
     }
  
     void setGroupArray( Group[] groupArray ){
        this.groupArray = groupArray;
     }
  }
  
  Group{
     boolean isChecked;
  
     boolean getIsChecked(){
     return isChecked;
    }
  
     void setIsChecked( boolean ischecked ){
        this.isChecked = ischecked;
      }
  }
  </code></pre>
  
  <p>id like to access this group array in my jsp.
  can i do that using this:</p>
  
  <pre><code>&lt;spring:form&gt;
    &lt;spring:checkbox path="groupArray[0].isChecked" /&gt;
    &lt;spring:checkbox path="groupArray[1].isChecked" /&gt;
    &lt;spring:checkbox path="groupArray[2].isChecked" /&gt;
  &lt;/spring:form&gt;
  </code></pre>
  
  <p>What i get is an exception:</p>
  
  <blockquote>
    <p>org.springframework.beans.NullValueInNestedPathException:
    Invalid property 'groupArray[0]' of
    bean class [PageForm]: Cannot access
    indexed value of property referenced
    in indexed property path
    'groupArray[0]': returned null</p>
  </blockquote>
  
  <p>Please help me.</p>
  
  <p>Thanks.</p>