### Question:
PropertyExpander { public static String expandSystemProperties(String input) { return expandProperties(input, System.getProperties()); } private  PropertyExpander(); static String expandProperties(String input, Map props); static String expandSystemProperties(String input);  }### Answer:
@Test void testSystemProperty() throws Exception { String expanded = PropertyExpander.expandSystemProperties("${java.home}"); assertEquals(expanded, System.getProperty("java.home"), "Expanded string doesn't match expected" ); }