static int clientPropertyInt( JComponent c, String key, int defaultValue ) {
		Object value = c.getClientProperty( key );
		return (value instanceof Integer) ? (int) value : defaultValue;
	}
Checks whether a client property of a component is an integer and returns its value.
If the client property is not set, or not an integer, defaultValue is returned.
flatlaf-core/src/main/java/com/formdev/flatlaf/FlatClientProperties.java