Scenario Tree describes how to drive automatic generation processes.
Indeed, a scenario transforms an input (XML files, Pojos) into a GENERATED XML file which describes the body of a part (Editor, Query, Detail UI…).
The default generation process which is driven by Scenario Tree provided by Scenario.xml file (see Scenario architecture), may contain defects. For instance, in our case, we want to make 3 improvements:

1. For Film entity, Hibernate generates a Pojo which maps the year property to a date. The property must be changed to an int which can have a value between 1900 and 2155.
2. For Film entity, property specialFeatures is a string corresponding to a set of values. MultiChoice control to display value is more appropriate.
3. All POJOs that contain a lastUpdate property must extend a ASuperLastUpdate class that initializes the property value to the current date when creating or modifying entity.

Making changes to Scenario Tree file means update the generation processes. The belowing example shows differents possiblities:

• New scenarios, generators, path elements, parameters can be specified or added to the Scenario Tree before launching or relaunching generation processes.
• Pojo rewriter for injecting changes in Pojos (e.g. org.adichatz.scenario.generation.SuperPojoRewriter is a java class for rewrite Pojo in order to add a super class).
• Specific features as new item value, validators or listeners can be added to the scenario tree.

These changes can be manually made by the developper inside the Scenario.xml file. A other way is to assemble changes inside a new Scenario tree stored in a specific xml file, inject these changes inside the current Scenario.xml file and launch needed generation processes.
In the example below, previously described needed change are incorparated.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<scenarioTree xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://www.adichatz.org/xsd/v0.9.1/generator/scenarioTree.xsd">
    <pathElements>
        <pathElement type="PROJECT" location="myscenario"/>
    </pathElements>
	<params>
    	<param id="devl.default.integer.pattern" value="#####"/>
    </params>
    <generators>
        <generator treeClassName="org.adichatz.generator.wrapper.TableWrapper" generatorClassName="org.mycompany.myscenario.generator.MyTableGenerator"/>
        <generator treeClassName="#CONTROLGENERATOR()" generatorClassName="org.mycompany.myscenario.generator.MyControlGenerator"/>
    </generators>
    <generationScenario scenarioClassName="org.adichatz.scenario.impl.PluginEntityScenario">
    	<modelPart>
    		<pojoRewriters>
	    		<pojoRewriter rewriterClassName="org.adichatz.scenario.generation.SuperPojoRewriter" propertyRegex="lastUpdate">
	    			<params>
	    				<param id="superClassURI" value="bundleclass://./#PACKAGENAME().model.ASuperLastUpdate"/>
	    				<param id="sourceURI" value="platform:/plugin/org.adichatz.template/template/src/ASuperLastUpdate.java"/>
	    			</params>
	    		</pojoRewriter>
			</pojoRewriters>
    	</modelPart>
		<propertyField id="lastUpdate">
        	<controlField xsi:type="dateTextType" enabled="false" style="SWT.BORDER | SWT.TIME"/>
        	<columnField xsi:type="tableColumnType" property="lastUpdate" sorted="true" style="SWT.CENTER"/>
		</propertyField>
        <pluginEntity entityURI="adi://././FilmMM">
        	<messages>
        		<message key="invalid.year.value" value="Invalid year '{0}'! Value must be between 1900 and 2155"/>
        	</messages>
            <propertyField id="releaseYear" pojoType="short">
		        <controlField xsi:type="formattedTextType" editPattern="####" format="Integer">
		        	<validators>
	           			<validator key="invalidYear" errorMessage="#MSG(film, invalid.year.value, #FV())">
	           				<errorWhen>return #FV() &lt; 1900 ||  #FV() &gt; 2155;</errorWhen>
	           			</validator>
		        	</validators>
		        </controlField>
            </propertyField>
            <propertyField id="specialFeatures">
		        <controlField xsi:type="multiChoiceType" multiChoiceType="String" values="Trailers,Commentaries,Deleted Scenes,Behind the Scenes" popupToolbar="true"/>
            </propertyField>
        </pluginEntity>
        <generationUnit scenarioClassName="org.adichatz.scenario.impl.GroupListNavigatorScenario" adiResourceURI="adi://groupNavigator/GroupNavigatorContent" type="NAVIGATOR"/>
    </generationScenario>
    <customPostAction injectInsideScenarioFile="true" generatePojo="true" generateEJB="true" generatePersistenceXml="true" deployEJB="true">
        <customGenerationUnit type="ENTITY" propertyRegex="lastUpdate"/>
        <customGenerationUnit type="DETAIL" propertyRegex="lastUpdate"/>
        <customGenerationUnit type="TABLE" entityRegex="Film"/>
        <customGenerationUnit type="MESSAGE_BUNDLE" entityRegex="Film"/>
    </customPostAction>
</scenarioTree>

Initial and final Scenario.xml can be respectively seen here and here.: