### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

Sending a message with body:
`"&quot;&quot;"`
is received on the consumer side with body:
`""""`

### Expected Behavior

Sending a message with body:
"&quot;&quot;"
is received on the consumer side with body:
"&quot;&quot;"

### How are you starting LocalStack?

Custom (please describe below)

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

Running localstack in docker desktop on Mac using helm chart

https://localstack.github.io/helm-charts
version 0.3.7
Image version: 0.14.3

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)



### Environment

```markdown
- OS: macOS Monterey
- LocalStack: 0.14.3
```


### Anything else?

_No response_
 = shape_members[name]
            ")
            if not location:
                continue
            if name not in parameters:
                # ignores optional keys
                continue
            key = member_shape.serialization.get("name", name)
            value = parameters[name]
            if value is None:
                continue
             == "header":
                response.headers[key] = self._serialize_header_value(member_shape, value)
            el == "headers":
                header_prefix = key
                self._serialize_header_map(header_prefix, response, value)
            el == "statusCode":
                response.status_code = int(value)
    def _serialize_header_map(self, prefix: str, response: HttpResponse, params: dict) -> None:
        """Serializes the header map for the location trait "headers"."""
        for key, val in params.items():
            actual_key = prefix + key
            response.headers[actual_key] = val
    def _serialize_header_value(self, shape: Shape, value: Any):
        """Serializtion trait "header"."""
        if shape.type_name == "timestamp":
            datetime_obj = parse_to_aware_datetime(value)
            timestamp_format = shape.serialization.get(
                "timestampFormat", self.HEADER_TIMESTAMP_FORMAT
            )
            return self._convert_timestamp_to_str(datetime_obj, timestamp_format)
        elif shape.type_name == "list":
            converted_value = [
                self._serialize_header_value(shape.member, v) for v in value if v is not None
            ]
            return ",".join(converted_value)
        elif shape.type_name == "boolean":
            # Set the header value to "true" if the given value is truthy, otherwise set the header value to "false".
            return "true" if value else "false"
        elif is_json_value_header(shape):
            # Serialize with no spaces after separators to save space in
            # the header.
            retu