@GetMapping("/") does not work in Elastic Beanstalk but works locally – Nginx

My Elastic Beanstalk envrionemnt has a health status of severe. I believe this is due to the fact that I am not handling health checks. This can be seen in my logs:

/var/log/nginx/access.log
----------------------------------------
172.31.75.161 - - [08/Nov/2021:13:21:41 +0000] "GET / HTTP/1.1" 404 116 "-" "ELB-HealthChecker/2.0" "-"
172.31.75.161 - - [08/Nov/2021:13:21:41 +0000] "GET / HTTP/1.1" 404 116 "-" "ELB-HealthChecker/2.0" "-"
...

43 connect() failed (111: Connection refused) while connecting to upstream, client: 172.XX.XX.XX, server: , request: "GET / HTTP/1.1", upstream: "http://172.XX.XX.XX:8080/"

This is my Docker file:

# Build stage 
# 
FROM maven:3.8.1-jdk-8 
ADD src /tmp/src
ADD pom.xml /tmp/pom.xml
RUN mvn -f /tmp/pom.xml clean package

#
# Package stage
#
FROM openjdk:8
COPY --from=0 /tmp/target/para-host-0.0.1-SNAPSHOT.jar /usr/local/lib/para.jar
EXPOSE 5000
ENTRYPOINT ["java","-jar","/usr/local/lib/para.jar"]

So my Spring Boot app runs on port 5000. This works locally and in Elastic Beanstalk.

What I have tried so far
I have tried using this dependency to add the health check functionality:

        <dependency>
            <groupId>
                org.springframework.boot
            </groupId>
            <artifactId>
                spring-boot-starter-actuator
            </artifactId>
        </dependency>

After that, I was able to run the server locally and hit the endpoint like this:
http://localhost:5000/actuator/health and got the response:

{
    "status": "UP"
}

(Is this even a Status Code?)

This is where its broken
In my load balancer in my Elastic Beanstalk environment, it says that my health check path is /. If I edit that value to /actuator/health/, then it simply reverts back to /. I have tried numerous times, even tried deleting it and creating a new one. Nothing. So I gave up on that. Instead, I figured, I would just make the path / return the status code for the health check.

So I made this:

    @GetMapping("/")
    public ResponseEntity<String> dummyMethod() {
        return new ResponseEntity<>("Hello from Dummy-Root-Method", HttpStatus.OK);
    }

thinking that now when the health check gets called, it will be successful, but this ALSO does not work. I am able to hit the / endpoint if I run the server locally, but when it is in Elastic Beanstalk, then it thinks the path does not exist. However, my other endpoints DO work. Here is a snippet of the working endpoint (getGroupResults) and then non-working endpoint (dummyMethod):

    @GetMapping("/get-group-results")
    public ResponseEntity<String> getGroupResults(@RequestBody ObjectNode objectNode)
            throws IOException, AddressException, MessagingException {
        String groupFolder = objectNode.get("group").asText();
        String sendToEmail = objectNode.get("email").asText();
        logger.info("Attempting to get results from folder: {}", groupFolder);
        String attachmentPath = Test.getMapFromGroupFolder(groupFolder).getAbsolutePath();
        String subject = "Results from parallenium";
        MailService.sendEmailWithAttachment(sendToEmail, attachmentPath, subject);
        return new ResponseEntity<>("Successfully sent results email", HttpStatus.OK);
    }

    /**
     * Dummy response for ELB so we do not receive errors
     * 
     * @return
     */
    @GetMapping("/")
    public ResponseEntity<String> dummyMethod() {
        return new ResponseEntity<>("Hello from Dummy-Root-Method", HttpStatus.OK);
    }

This is the response I get when trying to hit the /actuator/health/ endpoint in Elastic Beanstalk used like this http://para-server.us-east-1.elasticbeanstalk.com/actuator/health:

{
    "timestamp": "2021-11-08T16:56:20.785+00:00",
    "status": 404,
    "error": "Not Found",
    "path": "/"
}

Again, this works locally. Why?

Summary. What can I do?

1. Why can I not change the path to the health check in Elastic Beanstalk console?
2. Why does the root path / work locally, but not in my Elastic Beanstalk environment?

I simply want my environment to not be in red. It is working fine, but has health check errors.