CAMEL-18019: ensure some fields in the Kafka record fetcher are safe …

…for concurrent read

components/camel-kafka/src/main/java/org/apache/camel/component/kafka/KafkaFetchRecords.java

@@ -80,10 +80,13 @@ private enum State {
     private Exception lastError;
     private final KafkaConsumerListener consumerListener;
 
-    private boolean terminated;
-    private long currentBackoffInterval;
-    private boolean reconnect; // must be false at init (this is the policy whether to reconnect)
-    private boolean connected; // this is the state (connected or not)
+    // The following set of volatile variables are usually read from other threads,
+    // like from the health check thread. They are usually only read on those contexts.
+    private volatile boolean terminated;
+    private volatile long currentBackoffInterval;
+
+    private volatile boolean reconnect; // The reconnect must be false at init (this is the policy whether to reconnect).
+    private volatile boolean connected; // this is the state (connected or not)
 
     private volatile State state = State.RUNNING;