private static Row newRow(Schema schema) {
            ColumnValue[] values = new ColumnValue[schema.getColumnCount()];
            for (Column column : schema.getColumns()) {
                values[column.getIndex()] = newValue(column);
            }
            return new Row(values);
        }
Row is a container to stage values before adding into reference lists such as |stringReferences|.

|Row| works as a buffer against plugins that may add values incorrectly without |PageBuilderImpl#addRecord|.
It accepts just one value per column while |PageBuilderImpl| can double-store values regardless of columns.
Double-stored values are overwritten.
embulk-core/src/main/java/org/embulk/spi/PageBuilderImpl.java