Fix bug in JSON Schema for VCs and VPs.

Author: absoludity

schema/verifiable-credential/verifiable-credential-schema.json

@@ -161,10 +161,13 @@
 "properties": {
 "@context": {
 "type": "array",
-"contains": {
-"const": "https://www.w3.org/ns/credentials/v2"
-},
-"minItems": 1
+"prefixItems": [
+{
+"const": "https://www.w3.org/ns/credentials/v2"
+}
+],
+"minItems": 1,
+"uniqueItems": true
 },
 "id": {
 "type": "string"
@@ -316,4 +319,4 @@
 "credentialSubject"
 ],
 "additionalProperties": true
-}
+}