Force init of Unbox in log4j (#92377)

* Force init of Unbox in log4j

Some libaries have static initializers that require security manager
permissions. When this initialization occurs during normal operation, it
can cause security manager exceptions depending on where a logging call
is made.

This commit adds a place for static initialization of log4j utility
classes to be run, and specifically adds the Unbox class which wants to
read env vars.

closes #91964

Author: rjernst

docs/changelog/92377.yaml

@@ -0,0 +1,6 @@
+pr: 92377
+summary: Force init of Unbox in log4j
+area: Infra/Core
+type: bug
+issues:
+ - 91964

server/src/main/java/org/elasticsearch/common/logging/LogConfigurator.java

@@ -30,6 +30,7 @@
 import org.apache.logging.log4j.status.StatusData;
 import org.apache.logging.log4j.status.StatusListener;
 import org.apache.logging.log4j.status.StatusLogger;
+import org.apache.logging.log4j.util.Unbox;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.common.logging.internal.LoggerFactoryImpl;
 import org.elasticsearch.common.settings.Settings;
@@ -41,6 +42,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.PrintStream;
+import java.lang.invoke.MethodHandles;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.FileVisitOption;
 import java.nio.file.FileVisitResult;
@@ -122,6 +124,7 @@ public static void configure(final Environment environment, boolean useConsole)
         }
         configureESLogging();
         configure(environment.settings(), environment.configFile(), environment.logsFile(), useConsole);
+        initializeStatics();
     }
 
     public static void configureESLogging() {
@@ -144,6 +147,17 @@ public static void setNodeName(String nodeName) {
         NodeNamePatternConverter.setNodeName(nodeName);
     }
 
+    // Some classes within log4j have static initializers that require security manager permissions.
+    // Here we aggressively initialize those classes during logging configuration so that
+    // actual logging calls at runtime do not trigger that initialization.
+    private static void initializeStatics() {
+        try {
+            MethodHandles.publicLookup().ensureInitialized(Unbox.class);
+        } catch (IllegalAccessException impossible) {
+            throw new AssertionError(impossible);
+        }
+    }
+
     private static void checkErrorListener() {
         assert errorListenerIsRegistered() : "expected error listener to be registered";
         if (error.get()) {