Bug 155513 New behavior to create column binding names.
The rule is that: if a content element defines data set or column bindings, to refer bindings on container, it must use syntax like row._outer. So, ONLY check the data binding to which the new column is being added. That is, binding names can be same for content and container elements. For example, if the column binding is added to the data, only check column bindings on data. Do not need to concern column bindings on its container like table item. Make sure other teams know this change.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/elements/ReportItem.java
* @see org.eclipse.birt.report.model.core.DesignElement#getStrategy()
	 */
	public PropertySearchStrategy getStrategy( )
	{
		return ReportItemPropSearchStrategy.getInstance( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.core.DesignElement#checkStructureList(org.eclipse.birt.report.model.core.Module,
	 *      org.eclipse.birt.report.model.metadata.PropertyDefn, java.util.List,
	 *      org.eclipse.birt.report.model.api.core.IStructure)
	 */
	public void checkStructureList( Module module, PropertyDefn propDefn,
			List list, IStructure toAdd ) throws PropertyValueException
	{
		String propName = propDefn.getName( );
		if ( BOUND_DATA_COLUMNS_PROP.equals( propName ) )
		{
			List errorList = ColumnBindingNameValidator.getInstance( )
					.validateForAdding( getHandle( module ), propDefn, toAdd );
			if ( errorList.size( ) > 0 )
			{
				throw (PropertyValueException) errorList.get( 0 );
			}
		}
		super.checkStructureList( module, propDefn, list, toAdd );
	}
}