public static void registerCustomDefaultsSource( String packageName, ClassLoader classLoader ) {
		if( customDefaultsSources == null )
			customDefaultsSources = new ArrayList<>();
		customDefaultsSources.add( packageName );
		customDefaultsSources.add( classLoader );
	}
Registers a package where FlatLaf searches for properties files with custom UI defaults.
<p>
See {@link #registerCustomDefaultsSource(String)} for details.

@param packageName a package name (e.g. "com.myapp.resources")
@param classLoader a class loader used to find resources, or {@code null}
flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java