code: public static Value dateArray(@Nullable Iterable<Date> v) {
      return new DateArrayImpl(v == null, v == null ? null : immutableCopyOf(v));
    }
docs: Returns an {@code ARRAY<DATE>} value. The range [1678-01-01, 2262-01-01) is the legal interval
  for cloud spanner dates. A write to a date column is rejected if the value is outside of that
  interval.
  
  @param v the source of element values. This may be {@code null} to produce a value for which
  {@code isNull()} is {@code true}. Individual elements may also be {@code null}.