Fix JDK 21 findings in the JVM integrations

sentry-async-profiler/src/main/java/io/sentry/asyncprofiler/convert/JfrAsyncProfilerToSentryProfileConverter.java

@@ -83,7 +83,7 @@ private class ProfileEventVisitor implements EventCollector.Visitor {
     private final @NotNull JfrReader jfr;
     private final @NotNull Arguments args;
 
-    public ProfileEventVisitor(
+    ProfileEventVisitor(
         @NotNull SentryProfile sentryProfile,
         @NotNull SentryStackTraceFactory stackTraceFactory,
         @NotNull JfrReader jfr,

sentry-jul/src/main/java/io/sentry/jul/SentryHandler.java

@@ -40,6 +40,9 @@
 import org.slf4j.MDC;
 
 /** Logging handler in charge of sending the java.util.logging records to a Sentry server. */
+// temp fix for JDK 21: Constructors call overridable methods; making them final would break the
+// public API.
+@SuppressWarnings("this-escape")
 @Open
 public class SentryHandler extends Handler {
   public static final String MECHANISM_TYPE = "JulSentryHandler";

sentry-kafka/src/main/java/io/sentry/kafka/SentryKafkaConsumerTracing.java

@@ -247,7 +247,7 @@ private void finishTransaction(
 
     try {
       final double enqueuedTimeSeconds = Double.parseDouble(enqueuedTimeStr);
-      final double nowSeconds = DateUtils.millisToSeconds(System.currentTimeMillis());
+      final double nowSeconds = DateUtils.millisToSeconds((double) System.currentTimeMillis());
       final long latencyMs = (long) ((nowSeconds - enqueuedTimeSeconds) * 1000);
       return latencyMs >= 0 ? latencyMs : null;
     } catch (NumberFormatException ignored) {

sentry-kafka/src/main/java/io/sentry/kafka/SentryKafkaProducer.java

@@ -114,7 +114,8 @@ static final class SentryProducerHandler<K, V> implements InvocationHandler {
     }
 
     @Override
-    @SuppressWarnings("unchecked")
+    // temp fix for JDK 21: Proxy equals() is identity-based.
+    @SuppressWarnings({"unchecked", "ReferenceEquality"})
     public @Nullable Object invoke(
         final @NotNull Object proxy, final @NotNull Method method, final @Nullable Object[] args)
         throws Throwable {
@@ -236,7 +237,8 @@ private void maybeInjectHeaders(final @NotNull Headers headers, final @Nullable
         headers.remove(SENTRY_ENQUEUED_TIME_HEADER);
         headers.add(
             SENTRY_ENQUEUED_TIME_HEADER,
-            DateUtils.doubleToBigDecimal(DateUtils.millisToSeconds(System.currentTimeMillis()))
+            DateUtils.doubleToBigDecimal(
+                    DateUtils.millisToSeconds((double) System.currentTimeMillis()))
                 .toString()
                 .getBytes(StandardCharsets.UTF_8));
       } catch (Throwable t) {

sentry-logback/src/main/java/io/sentry/logback/SentryAppender.java

@@ -197,7 +197,8 @@ protected void captureLog(@NotNull ILoggingEvent loggingEvent) {
     final @NotNull SentryLogParameters params = SentryLogParameters.create(attributes);
     params.setOrigin("auto.log.logback");
 
-    Sentry.logger().log(sentryLevel, params, formattedMessage, arguments);
+    Sentry.logger()
+        .log(sentryLevel, params, formattedMessage, arguments != null ? arguments : new Object[0]);
   }
 
   @SuppressWarnings("deprecation")

sentry-opentelemetry/sentry-opentelemetry-bootstrap/src/main/java/io/sentry/opentelemetry/OtelContextScopesStorage.java

@@ -17,7 +17,7 @@ public final class OtelContextScopesStorage implements IScopesStorage {
 
   @Override
   public void init() {
-    /**
+    /*
      * We're currently overriding the storage mechanism to allow for cleanup of non closed OTel
      * scopes. These happen when using e.g. Sentry static API due to getCurrentScopes() invoking
      * Context.makeCurrent and then ignoring the returned lifecycle token (OTel Scope). After fixing

sentry-opentelemetry/sentry-opentelemetry-bootstrap/src/main/java/io/sentry/opentelemetry/SentryOtelThreadLocalStorage.java

@@ -29,6 +29,8 @@ public final class SentryOtelThreadLocalStorage implements ContextStorage {
 
   private static final ThreadLocal<Context> THREAD_LOCAL_STORAGE = new ThreadLocal<>();
 
+  // temp fix for JDK 21: Same identity check as OpenTelemetry's ThreadLocalContextStorage.
+  @SuppressWarnings("ReferenceEquality")
   @Override
   public Scope attach(Context toAttach) {
     if (toAttach == null) {

sentry-reactor/src/main/java/io/sentry/reactor/SentryReactorUtils.java

@@ -48,7 +48,7 @@ public static <T> Mono<T> withSentryForkedRoots(final @NotNull Mono<T> mono) {
    */
   public static <T> Mono<T> withSentryScopes(
       final @NotNull Mono<T> mono, final @NotNull IScopes scopes) {
-    /**
+    /*
      * WARNING: Cannot set the scopes as current. It would be used by others to clone again causing
      * shared scopes and thus leading to issues like unrelated breadcrumbs showing up in events.
      */
@@ -96,7 +96,7 @@ public static <T> Flux<T> withSentryForkedRoots(final @NotNull Flux<T> flux) {
    */
   public static <T> Flux<T> withSentryScopes(
       final @NotNull Flux<T> flux, final @NotNull IScopes scopes) {
-    /**
+    /*
      * WARNING: Cannot set the scopes as current. It would be used by others to fork again causing
      * shared scopes and thus leading to issues like unrelated breadcrumbs showing up in events.
      */