When executing:

```
s3AsyncClient.headBucket(HeadBucketRequest.builder()
                    .bucket("local-stack-test-bucket")
                    .build()).join();
```

We get this exception thrown (Java): java.util.concurrent.CompletionException: software.amazon.awssdk.services.s3.model.S3Exception: null (Service: S3, Status Code: 502, Request ID: null)

I narrowed this down to db4cddea4e4844c1241cca5ac22ecbde08e52064 and found the problem. PR incoming shortly.
def __init__(self, port, forward_url=None, ssl=False, host=None, update_listener=None, quiet=False, params={}):
        FuncThread.__init__(self, self.run_cmd, params, quiet=quiet)
        self.httpd = None
        self.port = port
        self.ssl = ssl
        self.quiet = quiet
        if forward_url:
            if '://' not in forward_url:
                forward_url = 'http://%s' % forward_url
            forward_url = forward_url.rstrip('/')
        self.forward_base_url = forward_url
        self.update_listener = update_listener
        self.server_stopped = False
        
        self.protocol_version = params.get('protocol_version') or 'HTTP/1.1'
        self.listen_host = host or ''
    def run_cmd(self, params):
        try:
            self.httpd = ThreadedHTTPServer((self.listen_host, self.port), GenericProxyHandler)
            if self.ssl:
                
                combined_file, cert_file_name, key_file_name = GenericProxy.create_ssl_cert(serial_number=self.port)
                self.httpd.socket = ssl.wrap_socket(self.httpd.socket,
                    server_side=True, certfile=combined_file)
            self.httpd.my_object = self
            self.httpd.serve_forever()
        except Exception as e:
            if not self.quiet or not self.server_stopped:
                LOG.error('Exception running proxy on port %s: %s %s' % (self.port, e, traceback.format_exc()))
    def stop(self, quiet=False):