XML is created with <null: attribute_name>

Steps:
1. Login to Alfresco JSF client as admin;
2. Create a web form with attached .xsd file;
3. Add the created web form to a web project;
4. Create xml content based on the added web form;
5. Open xml file->
<null:Category>
<null:Name>category1</null:Name>
<null:ParentCategory xsi:nil="false">/1.jpg</null:ParentCategory>
</null:Category>

Expected result:
5. it should be like that, shouldn't it?
<Category>
<Name>category1</Name>
<ParentCategory xsi:nil="false">/1.jpg</ParentCategory>
</Category>

OxanaBo