Replace deprecated ThrowableProxy with LogEvent#getThrown() in sentry-log4j2 (#5751)

* Replace deprecated ThrowableProxy with LogEvent#getThrown() in sentry-log4j2

* Add @nullable annotation and CHANGELOG entry

---------

Co-authored-by: Alexander Dinauer <adinauer@users.noreply.github.com>

Author: sahasan95

CHANGELOG.md

@@ -9,6 +9,7 @@
 - `SentryTagModifierNode.isImportantForBounds` now matches the default behavior and returns `true` ([#5789](https://github.com/getsentry/sentry-java/pull/5789))
 - Prevent a `StackOverflowError` when a `beforeSend`, `beforeBreadcrumb`, `beforeSendLog`, or `beforeEnvelope` callback triggers another capture (directly or through a logging integration such as Timber) ([#5737](https://github.com/getsentry/sentry-java/pull/5737))
   - Captures made from within a user callback (event, transaction, breadcrumb, log, envelope, or check-in) are now dropped while that callback runs, instead of recursing. Captures made by event processors are unaffected.
+- Replace deprecated `ThrowableProxy` with `LogEvent#getThrown()` in `sentry-log4j2` ([#5751](https://github.com/getsentry/sentry-java/pull/5751))
 
 ### Dependencies
 

sentry-log4j2/src/main/java/io/sentry/log4j2/SentryAppender.java

@@ -41,7 +41,6 @@
 import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
 import org.apache.logging.log4j.core.config.plugins.PluginElement;
 import org.apache.logging.log4j.core.config.plugins.PluginFactory;
-import org.apache.logging.log4j.core.impl.ThrowableProxy;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -274,13 +273,12 @@ protected void captureLog(@NotNull LogEvent loggingEvent) {
     event.setLogger(loggingEvent.getLoggerName());
     event.setLevel(formatLevel(loggingEvent.getLevel()));
 
-    final ThrowableProxy throwableInformation = loggingEvent.getThrownProxy();
-    if (throwableInformation != null) {
+    final @Nullable Throwable thrown = loggingEvent.getThrown();
+    if (thrown != null) {
       final Mechanism mechanism = new Mechanism();
       mechanism.setType(MECHANISM_TYPE);
       final Throwable mechanismException =
-          new ExceptionMechanismException(
-              mechanism, throwableInformation.getThrowable(), Thread.currentThread());
+          new ExceptionMechanismException(mechanism, thrown, Thread.currentThread());
       event.setThrowable(mechanismException);
     }