}
String selectorExpression = StringUtils.isEmpty(this.selectorExpression)
? DEFAULT_SELECTOR_EXPRESSION
: this.selectorExpression;
return new SelectorWatermark(this.acquireObjectStore(), this.variable, this.defaultExpression,
this.selector, selectorExpression);
}
else
{
return new UpdateExpressionWatermark(this.acquireObjectStore(), this.variable,