public static Builder builderFor(long snapshotId, SnapshotRefType type) {
    return new Builder(type, snapshotId);
  }
@Test
  public void testNoTypeFailure() {
    assertThatThrownBy(() -> SnapshotRef.builderFor(1L, null).build())
        .isInstanceOf(IllegalArgumentException.class)
        .hasMessage("Snapshot reference type must not be null");
  }