Review fixes for jedis-common:javaagent (#18070)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>

Author: otelbot[bot]

instrumentation/jedis/jedis-common/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/jedis/JedisRequestContext.java

@@ -12,9 +12,9 @@
 public class JedisRequestContext<T> {
   private static final ThreadLocal<JedisRequestContext<?>> contextThreadLocal = new ThreadLocal<>();
 
-  private Instrumenter<T, Void> instrumenter;
-  private T request;
-  private Context context;
+  @Nullable private Instrumenter<T, Void> instrumenter;
+  @Nullable private T request;
+  @Nullable private Context context;
   @Nullable private Throwable throwable;
 
   private JedisRequestContext() {}