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
import org.eclipse.birt.report.model.metadata.PropertyDefn;
/**
 * Base class for all report items. Represents anything that can be placed in a
 * layout container. Items have a size and position that are used in some of the
 * containers.
 * 
 */
public abstract class ReportItem extends StyledElement
		implements
			IReportItemModel
{
	/**
	 * Default constructor.
	 */
	public ReportItem( )
	{
	}
	/**
	 * Constructs the report item with an optional name.
	 * 
	 * @param theName
	 *            the optional name
	 */
	public ReportItem( String theName )
	{
		super( theName );
	}
	/**
	 * Returns the data set element, if any, for this element.
	 *