### Question:
DefaultMentionXDOMService implements MentionXDOMService { @Override public List<MacroBlock> listMentionMacros(XDOM xdom) { return xdom.getBlocks(DefaultMentionXDOMService::matchMentionMacro, Block.Axes.DESCENDANT); }  @Override List<MacroBlock> listMentionMacros(XDOM xdom); @Override Map<DocumentReference, List<String>> groupAnchorsByUserReference(List<MacroBlock> mentions,
        WikiReference wikiReference); @Override Optional<XDOM> parse(String payload, Syntax syntax);  }### Answer:
@Test void listMentionMacros() { List<MacroBlock> actual = this.xdomService.listMentionMacros(new XDOM(singletonList(new ParagraphBlock(asList( new NewLineBlock(), new GroupBlock(singletonList( new MacroBlock("mention", new HashMap<>(), true) )) ))))); assertEquals(1, actual.size()); Assertions.assertEquals(new MacroBlock("mention", new HashMap<>(), true), actual.get(0)); }