Exception when using logback socket appender

[rotscher]

Describe the bug
When using a socket appender with logback then the following exception is thrown:

16:29:16,325 |-INFO in ch.qos.logback.classic.net.SocketAppender[SOCKET] - remote peer localhost:9999: connection failed:  java.io.NotSerializableException: io.opentelemetry.javaagent.shaded.instrumentation.logback.mdc.v1_0.internal.UnionMap
	at java.io.NotSerializableException: io.opentelemetry.javaagent.shaded.instrumentation.logback.mdc.v1_0.internal.UnionMap
	at 	at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1187)
	at 	at java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1572)
	at 	at java.base/java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:443)
	at 	at ch.qos.logback.classic.spi.LoggingEventVO.writeObject(LoggingEventVO.java:182)
	at 	at jdk.internal.reflect.GeneratedMethodAccessor20.invoke(Unknown Source)
	at 	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at 	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at 	at java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1070)
	at 	at java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1516)
	at 	at java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1438)
	at 	at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1181)
	at 	at java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:350)
	at 	at ch.qos.logback.core.net.AutoFlushingObjectWriter.write(AutoFlushingObjectWriter.java:46)
	at 	at ch.qos.logback.core.net.AbstractSocketAppender.dispatchEvents(AbstractSocketAppender.java:236)
	at 	at ch.qos.logback.core.net.AbstractSocketAppender.connectSocketAndDispatchEvents(AbstractSocketAppender.java:194)
	at 	at ch.qos.logback.core.net.AbstractSocketAppender$1.run(AbstractSocketAppender.java:151)
	at 	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
	at 	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at 	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at 	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at 	at java.base/java.lang.Thread.run(Thread.java:833)

Steps to reproduce

Appender in logback.xml

    <appender name="SOCKET" class="ch.qos.logback.classic.net.SocketAppender">
        <remoteHost>localhost</remoteHost>
        <port>9999</port>
        <reconnectionDelay>5000</reconnectionDelay>
        <includeCallerData>false</includeCallerData>
        <queueSize>1024</queueSize>
        <eventDelayLimit>0</eventDelayLimit>
    </appender>

Workaround
Appender works when -Dotel.instrumentation.logback-mdc.enabled=false is set.

What version are you using?

• opentelemetry-javaagent: 1.25.1
• logback-classic: 1.4.7

Environment
Compiler: AdoptOpenJDK 17.0.7-1
OS: RedHat 8