Bug 121003 Data source property binding error
When there are two data source property binding, the second binding cannot be set.The exception will be reported: org.eclipse.birt.report.model.api.metadata.PropertyValueException: The value "odaDataSource" already exists. at org.eclipse.birt.report.model.api.validators.StructureListValidator.doCheckStructureList(StructureListValidator.java:223) at org.eclipse.birt.report.model.api.validators.StructureListValidator.validateForAdding(StructureListValidator.java:96) at org.eclipse.birt.report.model.core.DesignElement.checkStructureList(DesignElement.java:2642) at org.eclipse.birt.report.model.command.PropertyCommand.addItem(PropertyCommand.java:444) at org.eclipse.birt.report.model.api.DesignElementHandle.setPropertyBinding(DesignElementHandle.java:2086) at org.eclipse.birt.report.designer.internal.ui.dialogs.DataSourcePropertyBindingPage.performOk(DataSourcePropertyBindingPage.java:192)
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/validators/StructureListValidator.java
return doCheckStructureList( element.getModule( ),
				element.getElement( ), propDefn, list, toAdd );
	}
	/**
	 * Validates whether the list property specified by <code>propName</code>
	 * is invalid.
	 * @param module
	 *            the module
	 * @param element
	 *            the master page to validate
	 * @param propName
	 *            the name of the list property to validate
	 * 
	 * @return error list, each of which is the instance of
	 *         <code>SemanticException</code>.
	 */
	public List validate( Module module, DesignElement element,
			String propName )
	{
		ElementPropertyDefn propDefn = element.getPropertyDefn( propName );
		assert propDefn.getTypeCode( ) == PropertyType.STRUCT_TYPE
				&& propDefn.isList( );