[DPP] [BUG] EDC 0.7.3 incompatibility because of "@id" policy definition

[matbmoser]

Current Behavior

When the catalog is called in the new EDC 0.7.3 the policies are configured in a different way as mentioned in this ticket:
eclipse-edc/Connector#4179

This affects our digital product pass policy parsing logic.

Expected Behavior

Change the structure of the backend and frontend to support only DID Documents, with the "@id" at the left operand.

Fix in frontend here, to get the value by "@id":

digital-product-pass/dpp-frontend/src/utils/edcUtil.js

Lines 214 to 220 in d61dd71

	// Parse the left operand
	let rawLeftOperand = jsonUtil.get("odrl:leftOperand", constraint, ".", null);
	leftOperand = rawLeftOperand;
	// If is not a string convert the object or array to string
	if (typeof rawLeftOperand !== "string") {
	leftOperand = jsonUtil.toJsonString(rawLeftOperand)
	}

Fix in the backend here, to parse as DidDocument like the operator:

digital-product-pass/dpp-backend/digitalproductpass/src/main/java/org/eclipse/tractusx/digitalproductpass/core/models/negotiation/policy/Constraint.java

Lines 47 to 50 in d61dd71

	/** ATTRIBUTES **/
	@JsonProperty("odrl:leftOperand")
	@JsonAlias({"leftOperand","odrl:leftOperand"})
	String leftOperand;

[matbmoser]

I believe I have solved the problem ;)

[matbmoser]

Will be included in v4.0.0-rc2