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
assert reportItem != null;
			return reportItem.getProperty( propName );
		}
		
		Object value = extensionPropValues.get( propName );
		if ( value == null )
			return null;
		ElementPropertyDefn defn = (ElementPropertyDefn) getPropertyDefn( propName );
		if ( defn.getTypeCode( ) == IPropertyType.ELEMENT_REF_TYPE )
		{
			Module root = element.getRoot( );
			if ( root != null )
				return ReferenceValueUtil.resolveElementReference( root,
						element, defn, (ElementRefValue) value );
		}
		return extensionPropValues.get( propName );
	}
	/**
	 * Sets the value for extension property or extension model property.
	 * 
	 * @param prop
	 *            the definition of the property
	 * @param value
	 *            the value to set
	 */
	public void setExtensionProperty( ElementPropertyDefn prop, Object value )
	{
		if ( isExtensionXMLProperty( prop.getName( ) )
				&& hasOwnModel( prop.getName( ) ) )