*Serverless Java Container version*: `com.amazonaws.serverless:aws-serverless-java-container-springboot3:2.1.0-SNAPSHOT`

*Implementations:* `Spring Boot 3`

*Framework version:* `SpringBoot 3.2.5`

*Frontend service:* `FunctionUrl`

*Deployment method:* `SAM`

## Scenario
I still try to render freemarker templates via a spring boot lambda. I want to serve those lambdas via a FunctionUrl for simplicity reasons

## Expected behavior
When calling the path where the template is rendered, the response should contain the correct template with the correct headers.

## Actual behavior
For API GW Requests this works as expected. For FunctionUrl requests it does omit at least the `content-type` header and always replaces it with `application/json`

## Steps to reproduce
`sam build && sam deploy --guided` in this [modified sample for alt-pet-store](https://github.com/aws/serverless-java-container/compare/main...mircohacker:serverless-java-container:functionUrlReproducer)

## Full log output
### FunctionUrl

Cloudwatch:
```
2024-04-26T17:22:38.784+02:00 INIT_START Runtime Version: java:21.v15 Runtime Version ARN: arn:aws:lambda:eu-central-1::runtime:367cb4c78c9b9b4d4eb04656c9938e85fbed3f853a08f5e0a5f21a46326d3991
2024-04-26T17:22:39.879+02:00 2024-04-26T15:22:39.868Z INFO --- [ main] o.s.c.f.s.web.FunctionClassUtils : Main class: class com.amazonaws.serverless.sample.springboot3.Application
2024-04-26T17:22:39.893+02:00 2024-04-26T15:22:39.893Z INFO --- [ Thread-0] o.s.c.f.serverless.web.ServerlessMVC : Starting application with the following configuration classes:
2024-04-26T17:22:39.894+02:00 2024-04-26T15:22:39.894Z INFO --- [ Thread-0] o.s.c.f.serverless.web.ServerlessMVC : Application
2024-04-26T17:22:40.237+02:00 START RequestId: 95f605aa-b6f8-422e-ab8f-6db7f9be1269 Version: $LATEST
2024-04-26T17:22:41.295+02:00 . ____ _ __ _ _
2024-04-26T17:22:41.295+02:00 /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
2024-04-26T17:22:41.295+02:00 ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
2024-04-26T17:22:41.295+02:00 \\/ ___)| |_)| | | | | || (_| | ) ) ) )
2024-04-26T17:22:41.295+02:00 ' |____| .__|_| |_|_| |_\__, | / / / /
2024-04-26T17:22:41.295+02:00 =========|_|==============|___/=/_/_/_/
2024-04-26T17:22:41.296+02:00 :: Spring Boot :: (v3.2.5)
2024-04-26T17:22:41.521+02:00 2024-04-26T15:22:41.520Z INFO 10 --- [ Thread-0] c.a.s.p.s.AwsSpringWebRuntimeInitializer : AWS Environment: ===SNIP===
2024-04-26T17:22:41.525+02:00 2024-04-26T15:22:41.524Z INFO 10 --- [ Thread-0] c.a.s.p.s.AwsSpringWebRuntimeInitializer : AWS Handler: com.amazonaws.serverless.proxy.spring.SpringDelegatingLambdaContainerHandler
2024-04-26T17:22:41.577+02:00 2024-04-26T15:22:41.577Z INFO 10 --- [ Thread-0] o.s.boot.SpringApplication : Starting application using Java 21.0.2 with PID 10 (started by sbx_user1051 in /var/task)
2024-04-26T17:22:41.578+02:00 2024-04-26T15:22:41.578Z INFO 10 --- [ Thread-0] o.s.boot.SpringApplication : No active profile set, falling back to 1 default profile: "default"
2024-04-26T17:22:43.600+02:00 2024-04-26T15:22:43.600Z INFO 10 --- [ Thread-0] o.s.c.f.s.w.ServerlessAutoConfiguration : Configuring Serverless Web Container
2024-04-26T17:22:43.679+02:00 2024-04-26T15:22:43.679Z INFO 10 --- [ Thread-0] o.s.c.f.s.w.ServerlessAutoConfiguration : Initializing DispatcherServlet
2024-04-26T17:22:43.695+02:00 2024-04-26T15:22:43.695Z INFO 10 --- [ Thread-0] o.s.c.f.s.web.ServerlessServletContext : Initializing Spring DispatcherServlet 'dispatcherServlet'
2024-04-26T17:22:43.696+02:00 2024-04-26T15:22:43.696Z INFO 10 --- [ Thread-0] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2024-04-26T17:22:43.861+02:00 2024-04-26T15:22:43.861Z DEBUG 10 --- [ Thread-0] _.s.web.servlet.HandlerMapping.Mappings :
2024-04-26T17:22:43.861+02:00 c.a.s.s.s.c.IndexController:
2024-04-26T17:22:43.861+02:00 {GET [/index]}: something2()
2024-04-26T17:22:43.876+02:00 2024-04-26T15:22:43.876Z DEBUG 10 --- [ Thread-0] _.s.web.servlet.HandlerMapping.Mappings :
2024-04-26T17:22:43.876+02:00 c.a.s.s.s.c.PetsController:
2024-04-26T17:22:43.876+02:00 {POST [/pets]}: createPet(Pet)
2024-04-26T17:22:43.876+02:00 {GET [/pets]}: listPets(Optional,Principal)
2024-04-26T17:22:43.876+02:00 {GET [/pets/{petId}]}: listPets()
2024-04-26T17:22:43.876+02:00 {POST [/foo/{gender}/bar/{age}], produces [application/json]}: complexRequest(String,String,String,String)
2024-04-26T17:22:43.898+02:00 2024-04-26T15:22:43.898Z DEBUG 10 --- [ Thread-0] _.s.web.servlet.HandlerMapping.Mappings :
2024-04-26T17:22:43.898+02:00 o.s.b.a.w.s.e.BasicErrorController:
2024-04-26T17:22:43.898+02:00 { [/error], produces [text/html]}: errorHtml(HttpServletRequest,HttpServletResponse)
2024-04-26T17:22:43.898+02:00 { [/error]}: error(HttpServletRequest)
2024-04-26T17:22:43.939+02:00 2024-04-26T15:22:43.939Z DEBUG 10 --- [ Thread-0] _.s.web.servlet.HandlerMapping.Mappings : 'beanNameHandlerMapping' {}
2024-04-26T17:22:43.995+02:00 2024-04-26T15:22:43.995Z DEBUG 10 --- [ Thread-0] _.s.web.servlet.HandlerMapping.Mappings :
2024-04-26T17:22:43.995+02:00 c.a.s.s.s.c.IndexController:
2024-04-26T17:22:43.995+02:00 {GET [/index]}: something2()
2024-04-26T17:22:43.997+02:00 2024-04-26T15:22:43.997Z DEBUG 10 --- [ Thread-0] _.s.web.servlet.HandlerMapping.Mappings :
2024-04-26T17:22:43.997+02:00 c.a.s.s.s.c.PetsController:
2024-04-26T17:22:43.997+02:00 {POST [/pets]}: createPet(Pet)
2024-04-26T17:22:43.997+02:00 {GET [/pets]}: listPets(Optional,Principal)
2024-04-26T17:22:43.997+02:00 {GET [/pets/{petId}]}: listPets()
2024-04-26T17:22:43.997+02:00 {POST [/foo/{gender}/bar/{age}], produces [application/json]}: complexRequest(String,String,String,String)
2024-04-26T17:22:44.017+02:00 2024-04-26T15:22:44.016Z DEBUG 10 --- [ Thread-0] _.s.web.servlet.HandlerMapping.Mappings :
2024-04-26T17:22:44.017+02:00 o.s.b.a.w.s.e.BasicErrorController:
2024-04-26T17:22:44.017+02:00 { [/error], produces [text/html]}: errorHtml(HttpServletRequest,HttpServletResponse)
2024-04-26T17:22:44.017+02:00 { [/error]}: error(HttpServletRequest)
2024-04-26T17:22:44.178+02:00 2024-04-26T15:22:44.177Z INFO 10 --- [ Thread-0] o.s.web.servlet.DispatcherServlet : Completed initialization in 481 ms
2024-04-26T17:22:44.178+02:00 2024-04-26T15:22:44.178Z INFO 10 --- [ Thread-0] o.s.c.f.s.w.ServerlessAutoConfiguration : Initalized DispatcherServlet
2024-04-26T17:22:44.858+02:00 2024-04-26T15:22:44.857Z INFO 10 --- [ Thread-0] o.s.boot.SpringApplication : Started application in 4.694 seconds (process running for 6.032)
2024-04-26T17:22:44.861+02:00 2024-04-26T15:22:44.861Z INFO 10 --- [ Thread-0] o.s.c.f.serverless.web.ServerlessMVC : Application is started successfully.
2024-04-26T17:22:44.862+02:00 2024-04-26T15:22:44.862Z DEBUG 10 --- [ main] c.a.s.p.s.AwsSpringHttpProcessingUtils : Creating HttpServletRequest from: {"version":"2.0","routeKey":"$default","rawPath":"/index","rawQueryString":"","headers":{"x-amzn-tls-cipher-suite":"TLS_AES_128_GCM_SHA256","x-amzn-tls-version":"TLSv1.3","x-amzn-trace-id":"Root=1-662bc6be-691dba3b072d08df3ea4a37c","x-forwarded-proto":"https","host":"motbf3yoc5tldyrlv5zuprb4dy0xikik.lambda-url.eu-central-1.on.aws","x-forwarded-port":"443","x-forwarded-for":"SNIP","accept":"*/*","user-agent":"curl/8.6.0"},"requestContext":{"accountId":"anonymous","apiId":"motbf3yoc5tldyrlv5zuprb4dy0xikik","domainName":"motbf3yoc5tldyrlv5zuprb4dy0xikik.lambda-url.eu-central-1.on.aws","domainPrefix":"motbf3yoc5tldyrlv5zuprb4dy0xikik","http":{"method":"GET","path":"/index","protocol":"HTTP/1.1","sourceIp":"82.194.121.90","userAgent":"curl/8.6.0"},"requestId":"95f605aa-b6f8-422e-ab8f-6db7f9be1269","routeKey":"$default","stage":"$default","time":"26/Apr/2024:15:22:38 +0000","timeEpoch":1714144958361},"isBase64Encoded":false}
2024-04-26T17:22:45.064+02:00 2024-04-26T15:22:45.063Z WARN 10 --- [ main] c.a.s.s.s.filter.CognitoIdentityFilter : API Gateway context is null
2024-04-26T17:22:45.199+02:00 2024-04-26T15:22:45.198Z DEBUG 10 --- [ main] freemarker.cache : Couldn't find template in cache for "index.ftlh"("en", UTF-8, parsed); will try to load it.
2024-04-26T17:22:45.200+02:00 2024-04-26T15:22:45.199Z DEBUG 10 --- [ main] freemarker.cache : TemplateLoader.findTemplateSource("index_en.ftlh"): Not found
2024-04-26T17:22:45.201+02:00 2024-04-26T15:22:45.200Z DEBUG 10 --- [ main] freemarker.cache : TemplateLoader.findTemplateSource("index.ftlh"): Found
2024-04-26T17:22:45.202+02:00 2024-04-26T15:22:45.202Z DEBUG 10 --- [ main] freemarker.cache : Loading template for "index.ftlh"("en", UTF-8, parsed) from "class path resource [templates/index.ftlh]"
2024-04-26T17:22:45.276+02:00 2024-04-26T15:22:45.275Z DEBUG 10 --- [ main] freemarker.cache : "index.ftlh"("en", UTF-8, parsed) cached copy not yet stale; using cached.
2024-04-26T17:22:45.286+02:00 2024-04-26T15:22:45.285Z DEBUG 10 --- [ main] c.a.s.p.i.s.AwsHttpServletResponse : Response buffer flushed with 95 bytes, latch=1
2024-04-26T17:22:45.360+02:00 END RequestId: 95f605aa-b6f8-422e-ab8f-6db7f9be1269
2024-04-26T17:22:45.360+02:00
REPORT RequestId: 95f605aa-b6f8-422e-ab8f-6db7f9be1269 Duration: 5122.98 ms Billed Duration: 5123 ms Memory Size: 1024 MB Max Memory Used: 214 MB Init Duration: 1452.46 ms
REPORT RequestId: 95f605aa-b6f8-422e-ab8f-6db7f9be1269 Duration: 5122.98 ms Billed Duration: 5123 ms Memory Size: 1024 MB Max Memory Used: 214 MB Init Duration: 1452
```
curl (note the `Content-Type` header)
```
==SNIP==
< HTTP/1.1 200 OK
< Date: Fri, 26 Apr 2024 15:22:45 GMT
< Content-Type: application/json
< Content-Length: 95
< Connection: keep-alive
< x-amzn-RequestId: 95f605aa-b6f8-422e-ab8f-6db7f9be1269
< X-Amzn-Trace-Id: root=1-662bc6be-691dba3b072d08df3ea4a37c;parent=30b0674dce871ba0;sampled=0;lineage=097eefbb:0
<

hello from freemarker

1
2
3
4
5
6
7
8
9
10
* C
```

### Api GW

This is working as expected
```
2024-04-26T17:26:37.833+02:00 START RequestId: 869723e7-8b44-4c7f-961d-f1506030576d Version: $LATEST
2024-04-26T17:26:37.834+02:00 2024-04-26T15:26:37.834Z DEBUG 10 --- [ main] c.a.s.p.s.AwsSpringHttpProcessingUtils : Creating HttpServletRequest from: {"version":"1.0","resource":"$default","path":"/index","httpMethod":"GET","headers":{"Content-Length":"0","Host":"gimvqfn9q2.execute-api.eu-central-1.amazonaws.com","User-Agent":"curl/8.6.0","X-Amzn-Trace-Id":"Root=1-662bc7ad-0f01a64a540300ba387dae66","X-Forwarded-For":"82.194.121.90","X-Forwarded-Port":"443","X-Forwarded-Proto":"https","accept":"*/*"},"multiValueHeaders":{"Content-Length":["0"],"Host":["gimvqfn9q2.execute-api.eu-central-1.amazonaws.com"],"User-Agent":["curl/8.6.0"],"X-Amzn-Trace-Id":["Root=1-662bc7ad-0f01a64a540300ba387dae66"],"X-Forwarded-For":["82.194.121.90"],"X-Forwarded-Port":["443"],"X-Forwarded-Proto":["https"],"accept":["*/*"]},"queryStringParameters":null,"multiValueQueryStringParameters":null,"requestContext":{"accountId":"156176255525","apiId":"gimvqfn9q2","domainName":"gimvqfn9q2.execute-api.eu-central-1.amazonaws.com","domainPrefix":"gimvqfn9q2","extendedRequestId":"W1wjMhkmFiAEMog=","httpMethod":"GET","identity":{"accessKey":null,"accountId":null,"caller":null,"cognitoAmr":null,"cognitoAuthenticationProvider":null,"cognitoAuthenticationType":null,"cognitoIdentityId":null,"cognitoIdentityPoolId":null,"principalOrgId":null,"sourceIp":"82.194.121.90","user":null,"userAgent":"curl/8.6.0","userArn":null},"path":"/index","protocol":"HTTP/1.1","requestId":"W1wjMhkmFiAEMog=","requestTime":"26/Apr/2024:15:26:37 +0000","requestTimeEpoch":1714145197799,"resourceId":"$default","resourcePath":"$default","stage":"$default"},"pathParameters":null,"stageVariables":null,"body":null,"isBase64Encoded":false}
2024-04-26T17:26:37.899+02:00 2024-04-26T15:26:37.899Z WARN 10 --- [ main] c.a.s.s.s.filter.CognitoIdentityFilter : Cognito identity id in request is null
2024-04-26T17:26:37.900+02:00 2024-04-26T15:26:37.900Z DEBUG 10 --- [ main] freemarker.cache : TemplateLoader.findTemplateSource("index_en.ftlh"): Not found
2024-04-26T17:26:37.900+02:00 2024-04-26T15:26:37.900Z DEBUG 10 --- [ main] freemarker.cache : TemplateLoader.findTemplateSource("index.ftlh"): Found
2024-04-26T17:26:37.901+02:00 2024-04-26T15:26:37.901Z DEBUG 10 --- [ main] freemarker.cache : "index.ftlh"("en", UTF-8, parsed): using cached since class path resource [templates/index.ftlh] hasn't changed.
2024-04-26T17:26:37.901+02:00 2024-04-26T15:26:37.901Z DEBUG 10 --- [ main] freemarker.cache : "index.ftlh"("en", UTF-8, parsed) cached copy not yet stale; using cached.
2024-04-26T17:26:37.902+02:00 2024-04-26T15:26:37.901Z DEBUG 10 --- [ main] c.a.s.p.i.s.AwsHttpServletResponse : Response buffer flushed with 95 bytes, latch=1
2024-04-26T17:26:37.903+02:00 END RequestId: 869723e7-8b44-4c7f-961d-f1506030576d
2024-04-26T17:26:37.903+02:00 REPORT RequestId: 869723e7-8b44-4c7f-961d-f1506030576d Duration: 69.94 ms
```