public com.google.protobuf.ByteString getTimeColumnSpecIdBytes() {
    java.lang.Object ref = timeColumnSpecId_;
    if (ref instanceof java.lang.String) {
      com.google.protobuf.ByteString b =
          com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
      timeColumnSpecId_ = b;
      return b;
    } else {
      return (com.google.protobuf.ByteString) ref;
    }
  }
public com . google . protobuf . ByteString getTimeColumnSpecIdBytes ( ) { java . lang . Object ref = timeColumnSpecId_ ; if ( ref instanceof java . lang . String ) { com . google . protobuf . ByteString b = com . google . protobuf . ByteString . copyFromUtf8 ( ( java . lang . String ) ref ) ; timeColumnSpecId_ = b ; return b ; } else { return ( com . google . protobuf . ByteString ) ref ; } }
<pre>
column_spec_id of the time column. Only used if the parent dataset's
ml_use_column_spec_id is not set. Used to split rows into TRAIN, VALIDATE
and TEST sets such that oldest rows go to TRAIN set, newest to TEST, and
those in between to VALIDATE.
Required type: TIMESTAMP.
If both this column and ml_use_column are not set, then ML use of all rows
will be assigned by AutoML. NOTE: Updates of this field will instantly
affect any other users concurrently working with the dataset.
</pre>

<code>string time_column_spec_id = 2;</code>