make api classes final

Author: SylvainJuge

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/JmxTelemetry.java

@@ -12,7 +12,7 @@
 import java.util.function.Supplier;
 import javax.management.MBeanServerConnection;
 
-public class JmxTelemetry {
+public final class JmxTelemetry {
 
   private final JmxMetricInsight service;
   private final MetricConfiguration metricConfiguration;

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/JmxTelemetryBuilder.java

@@ -17,7 +17,7 @@
 import java.nio.file.Path;
 import java.util.logging.Logger;
 
-public class JmxTelemetryBuilder {
+public final class JmxTelemetryBuilder {
 
   private static final Logger logger = Logger.getLogger(JmxTelemetryBuilder.class.getName());