### Question:
PackageDeclarationTreeImpl extends BaseTreeImpl implements PackageDeclarationTree { @Override public List<Tree> children() { return children; } PackageDeclarationTreeImpl(TreeMetaData metaData, List<Tree> children); @Override List<Tree> children();  }### Answer:
@Test public void test() { Tree identifier = identifier("x"); PackageDeclarationTree tree = new PackageDeclarationTreeImpl(null, Collections.singletonList(identifier)); Assertions.assertThat(tree.children()).containsExactly(identifier); }