### 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_

            )
        return mime_type
    # Some extra utility methods subclasses can use.
    @staticmethod
    def _timestamp_iso8601(value: datetime) -> str:
        if value.microsecond > 0:
            timestamp_format = ISO8601_MICRO
        else:
            timestamp_format = ISO8601
        return value.strftime(timestamp_format)
    @staticmethod
    def _timestamp_unixtimestamp(value: datetime) -> float:
        return value.timestamp()
    @staticmethod
    def _timestamp_unixtimestampmillis(value: datetime) -> int:
        return int(value.timestamp() * 1000)
    def _timestamp_rfc822(self, value: datetime) -> str:
        if isinstance(value, datetime):
            value = self._timestamp_unixtimestamp(value)
        return formatdate(value, usegmt=True)
    def _convert_timestamp_to_str(
        self, value: Union[int, str, datetime], timestamp_format=None
    ) -> str:
        if timestamp_format is None:
            timestamp_format = self.TIMESTAMP_FORMAT
        
        datetime_obj = parse_to_aware_datetime(value)
        converter = getattr(self, "_timestamp_%s" % timestamp_format)
        final_value = converter(datetime_obj)
        return final_value
    @staticmethod
    def _get_serialized_name(shape: Shape, default_name: str) -> str:
        """
        Returns the serialized name for the shape if it exists.
        Otherwise, it will return the passed in default_name.
        """
        return shape.serialization.get("name", default_name)
    def _get_base64(self, value: Union[str, bytes]):
        """
        Returns the base64-encoded version of value, handling
        both strings and bytes. The returned value is a string
        via the default encoding.
        """
        if isinstance(value, str):
            value = value.encode(self.DEFAULT_ENCODING)
        return base64.b64encode(value).strip().decode(self.DEFAULT_ENCODING)
    def _encode_payload(self, body: Union[bytes, str]) -> bytes:
        if isinstance(body, str):
  