ShapeElement element = ...;
Property property = element.getProperty(PropertyID.AUTOSIZE);
if (property instanceof BooleanProperty)
{
BooleanProperty autoSize = (BooleanProperty) property.clone();
autoSize.setValue(true);
PropertyManager properties = new PropertyManager();
properties.addProperty(autoSize);
SessionManager.getInstance().createSession(project, "Test");
PresentationElementsManager.getInstance().setPresentationElementProperties(element, properties);
SessionManager.getInstance().closeSession(project);
}