@Test
  public void testAppendNoTimestamp() throws IOException {
    MutationProto mutation = getAppendMutation(null);
    Append append = ProtobufUtil.toAppend(mutation, null);
    assertEquals(HConstants.LATEST_TIMESTAMP, append.getTimestamp());
    append.getFamilyCellMap().values().forEach(cells -> cells
      .forEach(cell -> assertEquals(HConstants.LATEST_TIMESTAMP, cell.getTimestamp())));
  }
Older clients may not send along a timestamp in the MutationProto. Check that we default
correctly.
hbase-client/src/test/java/org/apache/hadoop/hbase/shaded/protobuf/TestProtobufUtil.java