Splunk JavaLogging 1.8.0 is not working with SpringBoot

Operating System: MacOS Ventura 13.2.1

I am following along with this tutorial to implement Splunk with SpringBoot (ApplicationRunner) by using the splunk-library-javalogging version 1.8.0. Below is the log4j2-spring.xml.

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
    <Appenders>
        <Console name="console" target="SYSTEM_OUT">
            <PatternLayout
                    pattern="%style{%d{ISO8601}} %highlight{%-5level }[%style{%t}{bright,blue}] %style{%C{10}}{bright,yellow}: %msg%n%throwable" />
        </Console>
        <SplunkHttp
                name="splunkhttp"
                url="remote_url"
                token="--token---"
                index="order_api_dev"
                sourcetype="log4j"
                messageFormat="text"
                disableCertificateValidation="true">
            <PatternLayout pattern="%m" />
        </SplunkHttp>

    </Appenders>

    <Loggers>
        <!-- LOG everything at INFO level -->
        <Root level="info">
            <AppenderRef ref="console" />
            <AppenderRef ref="splunkhttp" />
        </Root>
    </Loggers>
</Configuration>

When I run the application locally, I get this error java.lang.NoClassDefFoundError: com/google/gson/GsonBuilder:

2023-03-03 10:58:12,124 main ERROR Unable to invoke factory method in class com.splunk.logging.HttpEventCollectorLog4jAppender for element SplunkHttp: java.lang.NoClassDefFoundError: com/google/gson/GsonBuilder java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.build(PluginBuilder.java:138)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.createPluginObject(AbstractConfiguration.java:1122)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1047)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1039)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.doConfigure(AbstractConfiguration.java:651)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.initialize(AbstractConfiguration.java:249)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:295)
	at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:621)
	at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:285)
	at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadConfiguration(Log4J2LoggingSystem.java:227)
	at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadConfiguration(Log4J2LoggingSystem.java:193)
	at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:80)
	at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:60)
	at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.initialize(Log4J2LoggingSystem.java:169)
............
Caused by: java.lang.NoClassDefFoundError: com/google/gson/GsonBuilder
	at com.splunk.logging.HttpEventCollectorSender.<clinit>(HttpEventCollectorSender.java:46)
	at com.splunk.logging.HttpEventCollectorLog4jAppender.<init>(HttpEventCollectorLog4jAppender.java:86)
	at com.splunk.logging.HttpEventCollectorLog4jAppender.createAppender(HttpEventCollectorLog4jAppender.java:191)

When I include the maven dependency for Gson, I get this error java.lang.NoClassDefFoundError: okhttp3/OkHttpClient$Builder

Exception in thread "Timer-0" java.lang.NoClassDefFoundError: okhttp3/OkHttpClient$Builder
	at com.splunk.logging.HttpEventCollectorSender.startHttpClient(HttpEventCollectorSender.java:255)
	at com.splunk.logging.HttpEventCollectorSender.postEvents(HttpEventCollectorSender.java:325)

After including both dependencies and running, the application is stuck.

        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.10.1</version>
        </dependency>
        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>4.10.0</version>
        </dependency>

When I run it EKS without the above dependencies, I get this error java.lang.NoClassDefFoundError: okhttp3/Callback:

2023-03-03 05:05:22,436 main ERROR Unable to invoke factory method in class com.splunk.logging.HttpEventCollectorLog4jAppender for element SplunkHttp: java.lang.NoClassDefFoundError: okhttp3/Callback java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:119)
	at java.base/java.lang.reflect.Method.invoke(Method.java:578)
	at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.build(PluginBuilder.java:138)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.createPluginObject(AbstractConfiguration.java:1122)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1047)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1039)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.doConfigure(AbstractConfiguration.java:651)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.initialize(AbstractConfiguration.java:249)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:295)
	at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:621)
	at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:285)
	at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadConfiguration(Log4J2LoggingSystem.java:227)
	at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadConfiguration(Log4J2LoggingSystem.java:193)
	at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:80)
	at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:60)
	at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.initialize(Log4J2LoggingSystem.java:169)
..................
Caused by: java.lang.NoClassDefFoundError: okhttp3/Callback
	at com.splunk.logging.HttpEventCollectorLog4jAppender.<init>(HttpEventCollectorLog4jAppender.java:86)
	at com.splunk.logging.HttpEventCollectorLog4jAppender.createAppender(HttpEventCollectorLog4jAppender.java:191)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)

Start with the supplied log4j2-spring.xml and Maven dependency declarations, then trace the HttpEventCollectorLog4jAppender and HttpEventCollectorSender stack frames. Reproduce the missing Gson and okhttp classes in a Spring Boot application and establish what dependency setup allows startup and Splunk logging to work without the reported errors.