Bug 189622 DesignElementHandle.getMethods( ) shouldn't return null value
The return type of DesignElementHandle.getMethods( ) is List; if the design element handle doesn't have script methods, then it return null value. The return value is empty list will be better.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/extension/PeerExtensibilityProvider.java
* 
	 * @param propName
	 *            name of the property to check
	 * @return true if the property is XML type and holds the serialized XML
	 *         value for extension model properties, otherwise false
	 */
	public boolean isExtensionXMLProperty( String propName )
	{
		ExtensionElementDefn extDefn = getExtDefn( );
		if ( extDefn != null )
		{
			ElementPropertyDefn propDefn = (ElementPropertyDefn) extDefn
					.getProperty( propName );
			if ( propDefn != null && propDefn.hasOwnModel( )
					&& IPropertyType.XML_TYPE == propDefn.getTypeCode( ) )
				return true;
		}
		return false;
	}
	/**
	 * Tests whether the property is the extension property which holds the
	 * serialized XML value for extension model properties. The property type
	 * should be XML.
	 * 
	 * @param propName
	 *            name of the property to check
	 * @return true if the property is XML type and holds the serialized XML
	 *         value for extension model properties, otherwise false
	 */
	private boolean hasOwnModel( String propName )