### Question:
IdUtils { public static String getPrefixedId(final String prefixId, final String rawId) { return Stream.of(prefixId, rawId) .filter(s -> !isEmpty(s)) .collect(Collectors.joining(SEPARATOR_DELIMITER)); }  static String getPrefixedId(final String prefixId,
                                       final String rawId); static String getRawId(final String prefixedId); static String getComposedId(final String... parts); static String getShapeId(final JSIDMNDiagram diagram,
                                    final List<String> dmnElementIds,
                                    final String dmnElementId); static String getEdgeId(final JSIDMNDiagram diagram,
                                   final List<String> dmnElementIds,
                                   final String dmnElementId); static String uniqueId();  }### Answer:
@Test public void testGetPrefixedId() { assertEquals("1111#2222", getPrefixedId("1111", "2222")); assertEquals("2222", getPrefixedId("", "2222")); assertEquals("2222", getPrefixedId(null, "2222")); }