# Type of request: This is a ...
[ ] bug report
[x] feature request

# Detailed description
As a Developer,
I want to be able to simulate BadDigest and InvalidDigest errors,
So that I can test the error handling logic

## Expected behavior
https://docs.aws.amazon.com/AmazonS3/latest/API/ErrorResponses.html
BadDigest: The Content-MD5 you specified did not match what we received.
InvalidDigest: The Content-MD5 you specified is not valid.

## Actual behavior
localstack returns InvalidDigest when MD5 does not match payload.


""" Helper class to convert JSON documents with datetime, decimals, or bytes. """
    def default(self, o):
        if isinstance(o, decimal.Decimal):
            if o % 1 > 0:
                return float(o)
            else:
                return int(o)
        if isinstance(o, (datetime, date)):
            return str(o)
        if isinstance(o, six.binary_type):
            return to_str(o)
        try:
            return super(CustomEncoder, self).default(o)
        except Exception:
            return None
class ShellCommandThread(FuncThread):