Did integration

[wistefan]

Proposed changes

The changes allow the usage of certificates as defined by gaia-x for the i4Trust functionality. Beside that, it makes the policy-implementation more compliant with the iShare-Spec(e.g. attributes and identifiers are not longer mandatory).

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality
  to not work as expected)

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CLA Assistant Lite bot All contributors have signed the CLA ✍️

[wistefan]

I have read the CLA Document and I hereby sign the CLA