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
/*******************************************************************************
 * Copyright (c) 2004 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/
package org.eclipse.birt.report.model.elements;
import java.util.List;
import org.eclipse.birt.report.model.api.core.IStructure;
import org.eclipse.birt.report.model.api.metadata.PropertyValueException;
import org.eclipse.birt.report.model.api.validators.ColumnBindingNameValidator;
import org.eclipse.birt.report.model.api.validators.ElementReferenceValidator;
import org.eclipse.birt.report.model.core.DesignElement;
import org.eclipse.birt.report.model.core.Module;
import org.eclipse.birt.report.model.core.PropertySearchStrategy;
import org.eclipse.birt.report.model.core.StyledElement;
import org.eclipse.birt.report.model.elements.interfaces.IReportItemModel;
import org.eclipse.birt.report.model.elements.strategy.ReportItemPropSearchStrategy;
import org.eclipse.birt.report.model.metadata.ElementRefValue;