In an AS2 message, the header “disposition-notification-options” allows the client to request an ordered list of MIC algorithms, e.g. like “signed-receipt-micalg=optional, sha1”.
According to RFC4130, section 7.3:

The currently supported values for MIC algorithm <micalg> values are:

    Algorithm   Value Used
    ---------    -------
     SHA-1        sha1
     MD5          md5

Since the RFC originates from 2005, there are more secure hashing algorithms in use (e.g. sha256).

Would it be an option to extend the list of allowed MIC algorithms in AS2MicAlgorithm by

sha256
sha384
sha512

If someone finds the time to raise a JIRA issue, I would be glad to contribute a patch.