DBZ-2862 Add comments, minor modifications

debezium-interceptor/src/main/java/io/debezium/tracing/DebeziumTracingProducerInterceptor.java

@@ -36,13 +36,28 @@ public class DebeziumTracingProducerInterceptor<K, V> implements ProducerInterce
     private Object interceptorInstance;
     private Method onSendMethod;
 
+    /**
+     * The constructor for the DebeziumTracingProducerInterceptor.
+     * <p>
+     * In this interceptor, we use a dynamic approach to handle the OpenTelemetry tracing interceptor due to versioning issues.
+     * The problem arises because different versions of OpenTelemetry have their tracing interceptor in different packages.
+     * For example, in versions before 1.23.0, the tracing interceptor is in the "io.opentelemetry.instrumentation.kafkaclients" package,
+     * but from version 1.23.0 onwards, it is in the "io.opentelemetry.instrumentation.kafkaclients.v2_6" package.
+     * <p>
+     * The OpenTelemetry interceptor is also part of an alpha package, which means it's subject to change,
+     * and there is no guarantee of backward compatibility. That's why a dynamic approach is used here.
+     * We maintain an array of possible class names (InterceptorVersion) for the OpenTelemetry tracing interceptor,
+     * and we attempt to instantiate one of them at runtime. We also use reflection to access the 'onSend' method from the interceptor.
+     * <p>
+     * This allows the Debezium Kafka Connector to work with different versions of OpenTelemetry.
+     */
     public DebeziumTracingProducerInterceptor() {
-        InterceptorVersion[] versions = {
-                new InterceptorVersion("io.opentelemetry.instrumentation.kafkaclients.v2_6.TracingProducerInterceptor"),
-                new InterceptorVersion("io.opentelemetry.instrumentation.kafkaclients.TracingProducerInterceptor"),
+        OpenTelemetryInterceptorVersion[] versions = {
+                new OpenTelemetryInterceptorVersion("io.opentelemetry.instrumentation.kafkaclients.v2_6.TracingProducerInterceptor"),
+                new OpenTelemetryInterceptorVersion("io.opentelemetry.instrumentation.kafkaclients.TracingProducerInterceptor"),
         };
 
-        for (InterceptorVersion version : versions) {
+        for (OpenTelemetryInterceptorVersion version : versions) {
             interceptorInstance = version.createInstance();
             if (interceptorInstance != null) {
                 onSendMethod = version.getMethod("onSend", ProducerRecord.class);
@@ -52,7 +67,7 @@ public DebeziumTracingProducerInterceptor() {
             }
         }
 
-        if (interceptorInstance == null || onSendMethod == null) {
+        if (onSendMethod == null) {
             LOGGER.error("Unable to instantiate any known version of the interceptor");
             throw new IllegalStateException("Unable to instantiate interceptor");
         }

debezium-interceptor/src/main/java/io/debezium/tracing/OpenTelemetryInterceptorVersion.java

@@ -10,13 +10,25 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class InterceptorVersion {
-    private static final Logger LOGGER = LoggerFactory.getLogger(InterceptorVersion.class);
+/**
+ * This class represents a specific version of the OpenTelemetry interceptor by its class name.
+ * <p>
+ * An instance of this class attempts to dynamically load the OpenTelemetry interceptor class from the provided class name.
+ * If the class is present in the classpath (meaning that the relevant version of OpenTelemetry is being used),
+ * it gets loaded and methods can be retrieved from it for further invocation.
+ * If the class is not present, all operations gracefully degrade to return null, indicating that the version is not available.
+ * <p>
+ * This dynamic approach allows the Debezium Kafka Connector to interact with different versions of the OpenTelemetry interceptor,
+ * without having a direct compile-time dependency. It provides a level of abstraction over the changes in the OpenTelemetry interceptor's
+ * class name and package between different versions of OpenTelemetry.
+ */
+public class OpenTelemetryInterceptorVersion {
+    private static final Logger LOGGER = LoggerFactory.getLogger(OpenTelemetryInterceptorVersion.class);
 
     private final String className;
     private Class<?> interceptorClass;
 
-    public InterceptorVersion(String className) {
+    public OpenTelemetryInterceptorVersion(String className) {
         this.className = className;
         try {
             this.interceptorClass = Class.forName(className);
@@ -37,7 +49,7 @@ public Object createInstance() {
             return interceptorClass.getDeclaredConstructor().newInstance();
         }
         catch (Exception e) {
-            LOGGER.error("Unable to instantiate {}", className, e);
+            LOGGER.debug("Unable to instantiate {}", className, e);
             return null;
         }
     }
@@ -50,7 +62,7 @@ public Method getMethod(String name, Class<?>... parameterTypes) {
             return interceptorClass.getMethod(name, parameterTypes);
         }
         catch (Exception e) {
-            LOGGER.error("Unable to get method {} from {}", name, className, e);
+            LOGGER.debug("Unable to get method {} from {}", name, className, e);
             return null;
         }
     }