Build error: LDNInboxTest, JsonObject cannot be cast to JsonString

[pdurbin]

I'm getting this error locally when I do mvn package:

[INFO] Results:
[INFO] 
[ERROR] Errors: 
[ERROR]   LDNInboxTest.testAcceptMessage_NoDatasetFound:235 » ClassCast class org.eclipse.parsson.JsonObjectBuilderImpl$JsonObjectImpl cannot be cast to class jakarta.json.JsonString (org.eclipse.parsson.JsonObjectBuilderImpl$JsonObjectImpl and jakarta.json.JsonString are in unnamed module of loader 'app')
[ERROR]   LDNInboxTest.testAcceptRelationshipAnnouncementMessage:183 » ClassCast class org.eclipse.parsson.JsonObjectBuilderImpl$JsonObjectImpl cannot be cast to class jakarta.json.JsonString (org.eclipse.parsson.JsonObjectBuilderImpl$JsonObjectImpl and jakarta.json.JsonString are in unnamed module of loader 'app')
[ERROR]   LDNInboxTest.testAcceptRelationshipAnnouncementMessage_IsSupplementTo:214 » ClassCast class org.eclipse.parsson.JsonObjectBuilderImpl$JsonObjectImpl cannot be cast to class jakarta.json.JsonString (org.eclipse.parsson.JsonObjectBuilderImpl$JsonObjectImpl and jakarta.json.JsonString are in unnamed module of loader 'app')
[INFO] 
[ERROR] Tests run: 2015, Failures: 0, Errors: 3, Skipped: 37
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  36.105 s
[INFO] Finished at: 2026-02-24T10:56:46-05:00
[INFO] ------------------------------------------------------------------------

Other places I've seen this error:

• https://jenkins.dataverse.org/job/IQSS-dataverse-develop/2390/consoleFull
• https://jenkins.dataverse.org/job/IQSS-Dataverse-Develop-PR/view/change-requests/job/PR-12159/8/console
• https://jenkins.dataverse.org/job/IQSS-Dataverse-Develop-PR/job/PR-12129/6/console

Last discussed here:

• Jenkins is failing ❌ 🔥 #12023

[pdurbin]

[ERROR] LDNInboxTest.testAcceptMessage_NoDatasetFound:235 » ClassCast class org.eclipse.parsson.JsonObjectBuilderImpl$JsonObjectImpl cannot be cast to class jakarta.json.JsonString (org.eclipse.parsson.JsonObjectBuilderImpl$JsonObjectImpl and jakarta.json.JsonString are in unnamed module of loader 'app')

Here's the incoming JSON when you run mvn test -Dtest=LDNInboxTest#testAcceptMessage_NoDatasetFound:

{
  "@id": "urn:uuid:91af0274-d675-480d-a19d-a1a1f2eaa3f5",
  "@type": "https://www.w3.org/ns/activitystreams#Relationship",
  "https://www.w3.org/ns/activitystreams#relationship": {
    "@id": "http://purl.org/spar/datacite/Cites"
  },
  "https://www.w3.org/ns/activitystreams#subject": {
    "@id": "https://doi.org/10.1234/example-publication"
  },
  "https://www.w3.org/ns/activitystreams#object": {
    "@id": "doi:10.5072/FK2/TESTID"
  }
}

The code is using https://www.w3.org/ns/activitystreams#subject as a key and trying to get a String out of it. But as can be seen above and in the error, it's an object.