@CheckForNull
  @Override
  public Set<Path> branchChangedFiles(String targetBranchName, Path rootBaseDir) {
    return Optional.ofNullable((branchChangedFilesWithFileMovementDetection(targetBranchName, rootBaseDir)))
      .map(GitScmProvider::extractAbsoluteFilePaths)
      .orElse(null);
  }
@Test
  public void branchChangedFiles_should_return_null_when_branch_nonexistent() {
    assertThat(newScmProvider().branchChangedFiles("nonexistent", worktree)).isNull();
  }