To specify size constraints, you can use the SpringLayout.Constraints class.
Here's an example that demonstrates how to set size constraints:
SpringLayout.Constraints constraints = layout.getConstraints(component);
constraints.setWidth(Spring.constant(100));
constraints.setHeight(Spring.constant(50));
In this example, component is the component for which you want to set the size constraints. The setWidth() and setHeight() methods are used to specify the width and height constraints, respectively.