public static String gitCommitId() {
    ensureLoaded();
    return commitId;
  }
@Test
  public void testGitCommitId() {
    assertThat(IcebergBuild.gitCommitId())
        .as("Should not use unknown commit ID")
        .isNotEqualTo("unknown");
    assertThat(
            Pattern.compile("[0-9a-f]{40}")
                .matcher(IcebergBuild.gitCommitId().toLowerCase(Locale.ROOT)))
        .as("Should be a hexadecimal string of 20 bytes")
        .matches();
  }