chore: add example for provider state injection where the value is missing

Author: Ronald Holshausen

provider/pact-jvm-provider-junit5/src/test/groovy/au/com/dius/pact/provider/junit5/StateInjectedProviderTest.groovy

@@ -64,7 +64,9 @@ class StateInjectedProviderTest {
         .withRequestBody(matchingJsonPath('$.[?(@.entityName =~ /\\w+/)]'))
         .willReturn(aResponse()
           .withStatus(201)
-          .withHeader('Location', "http://localhost:${server.port()}/entity/1234"))
+          .withHeader('Location', "http://localhost:${server.port()}/entity/1234")
+          .withHeader('Content-Type', 'application/json')
+          .withBody('{"accountId": "4beb44f1-53f7-4281-abcd-12c06d682067"}'))
     )
   }
 

provider/pact-jvm-provider-junit5/src/test/resources/pacts/xml-in-json-pact.json

@@ -36,7 +36,30 @@
         }
       },
       "response": {
-        "status": 201
+        "status": 201,
+        "body": {
+          "accountId": "4beb44f1-53f7-4281-a78b-12c06d682067"
+        },
+        "matchingRules": {
+          "body": {
+            "$.accountId": {
+              "matchers": [
+                {
+                  "match": "type"
+                }
+              ],
+              "combine": "AND"
+            }
+          }
+        },
+        "generators": {
+          "body": {
+            "$.accountId": {
+              "type": "ProviderState",
+              "expression": "${accountId}"
+            }
+          }
+        }
       }
     }
   ],