Fix the example code for skipping records to work properly (#719)

Fixed the example code for skipping records to work properly.
Previously, the example code did not work correctly because retriesCount was constantly 0.

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Co-authored-by: Roman Kolesnev <88949424+rkolesnev@users.noreply.github.com>
Co-authored-by: John Byrne <33546417+johnbyrnejb@users.noreply.github.com>

README.adoc

@@ -823,7 +823,7 @@ Implementing a https://github.com/confluentinc/parallel-consumer/issues/196[max
 
         pc.poll(context -> {
             var consumerRecord = context.getSingleRecord().getConsumerRecord();
-            Long retryCount = retriesCount.computeIfAbsent(consumerRecord, ignore -> 0L);
+            Long retryCount = retriesCount.compute(consumerRecord, (key, oldValue) -> oldValue == null ? 0L : oldValue + 1);
             if (retryCount < maxRetries) {
                 processRecord(consumerRecord);
                 // no exception, so completed - remove from map

parallel-consumer-examples/parallel-consumer-example-core/src/main/java/io/confluent/parallelconsumer/examples/core/CoreApp.java

@@ -143,7 +143,7 @@ void maxRetries() {
 
         pc.poll(context -> {
             var consumerRecord = context.getSingleRecord().getConsumerRecord();
-            Long retryCount = retriesCount.computeIfAbsent(consumerRecord, ignore -> 0L);
+            Long retryCount = retriesCount.compute(consumerRecord, (key, oldValue) -> oldValue == null ? 0L : oldValue + 1);
             if (retryCount < maxRetries) {
                 processRecord(consumerRecord);
                 // no exception, so completed - remove from map