Indexing with simple expression broken in Apache Camel 2.18 - apache-camel

Question

The following sample code works fine with all versions of Camel, excluding 2.18.x
from("direct:process")
.process(new Processor() {
public void process(Exchange exchange) {
List<String> alist = new ArrayList<String>();
alist.add("1");
alist.add("99");
exchange.getIn().setHeader("ITEMS", alist);
exchange.getIn().setHeader("TOTAL_LOOPS", alist.size());
}
})
.loop(simple("${header.TOTAL_LOOPS}", Integer.class))
.setHeader("item", simple("${header.ITEMS[${property.CamelLoopIndex}]}", String.class))
.log(LoggingLevel.INFO, LOG_CLASS_NAME, simple("item = ${header.item} and TOTAL_MAPS = ${header.TOTAL_LOOPS}").getText())
.end()
.end();
However with 2.18.x, the following exception gets thrown:
2017-02-03 21:13:31 ERROR DefaultErrorHandler:204 - Failed delivery
for (MessageId: ID-CATL0W10D4DG4R1-55822-1486174410756-0-1 on
ExchangeId: ID-CATL0W10D4DG4R1-55822-1486174410756-0-2). Exhausted
after delivery attempt: 1 caught:
org.apache.camel.language.bean.RuntimeBeanExpressionException: Failed
to invoke method: [${property.CamelLoopIndex}] on java.util.ArrayList
due to: java.lang.IndexOutOfBoundsException: Key:
${property.CamelLoopIndex} not found in bean: [1, 99] of type:
java.util.ArrayList using OGNL path [[${property.CamelLoopIndex}]]