CARDS-2820: Move to Java 21

[sdumitriu]

To test:

• upgrade to Java 21 or 24
• upgrade Maven to 3.8.7
• build
• run
• make sure it starts correctly
• check that backend computed answers work

[acrowthe]

Backend computed answer are not working reliably for me:
On the Backend Computed Test - Invalid Names test form, the first 4 computed questions do not work in the backend and there are a lot of logged warning and error messages including:

05.01.2026 14:29:52.492 *WARN* [127.0.0.1 [1767641392386] POST /Forms/cbae45fb-e7b0-4493-a2ce-f30844f2b3c4 HTTP/1.1] io.uhndata.cards.forms.internal.ExpressionUtilsImpl Evaluating the expression for question Node[NodeDelegate{tree=/Questionnaires/BackendComputedTest/computedquestions/question4c_computed: { jcr:primaryType = cards:Question, jcr:createdBy = sling-jcr-content-loader, expression = return "The first value from Question 4 is " + @{question4_multi?};, minAnswers = 0, entryMode = computed, jcr:created = 2026-01-05T14:24:05.143-05:00, text = Question 4c Computed. Displays "The first value from Question 4 is " and the first value, if any, sling:resourceSuperType = cards/ResourcePart, maxAnswers = 1, jcr:uuid = af68f199-879f-4621-bb0b-82515be87255, sling:resourceType = cards/Question, displayMode = formatted, dataType = text}}] failed: Failure running script NO_SCRIPT_NAME: ReferenceError: "arg0" is not defined. (NO_SCRIPT_NAME#1)
javax.script.ScriptException: Failure running script NO_SCRIPT_NAME: ReferenceError: "arg0" is not defined. (NO_SCRIPT_NAME#1)
	at org.apache.sling.scripting.javascript.internal.RhinoJavaScriptEngine$SlingCompiledScript.eval(RhinoJavaScriptEngine.java:320) [org.apache.sling.scripting.javascript:3.1.4]
	at org.apache.sling.scripting.javascript.internal.RhinoJavaScriptEngine.eval(RhinoJavaScriptEngine.java:155) [org.apache.sling.scripting.javascript:3.1.4]
	at org.apache.sling.scripting.api.AbstractSlingScriptEngine.eval(AbstractSlingScriptEngine.java:44) [org.apache.sling.scripting.api:2.2.0]
	at java.scripting/javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:231)
	at io.uhndata.cards.forms.internal.ExpressionUtilsImpl.evaluate(ExpressionUtilsImpl.java:109) [io.uhndata.cards.data-model-forms-impl:0.9.36.SNAPSHOT]
	at io.uhndata.cards.forms.internal.ComputedAnswersEditor.computeAnswer(ComputedAnswersEditor.java:183) [io.uhndata.cards.data-model-forms-impl:0.9.36.SNAPSHOT]
	at io.uhndata.cards.forms.internal.ComputedAnswersEditor.lambda$handleLeave$3(ComputedAnswersEditor.java:169) [io.uhndata.cards.data-model-forms-impl:0.9.36.SNAPSHOT]
	...

05.01.2026 14:29:52.505 *WARN* [127.0.0.1 [1767641392386] POST /Forms/cbae45fb-e7b0-4493-a2ce-f30844f2b3c4 HTTP/1.1] io.uhndata.cards.forms.internal.ExpressionUtilsImpl Parsing Object [] to JSObject failed: Failure running script NO_SCRIPT_NAME: ReferenceError: "Java" is not defined. (NO_SCRIPT_NAME#1)
javax.script.ScriptException: Failure running script NO_SCRIPT_NAME: ReferenceError: "Java" is not defined. (NO_SCRIPT_NAME#1)
	at org.apache.sling.scripting.javascript.internal.RhinoJavaScriptEngine$SlingCompiledScript.eval(RhinoJavaScriptEngine.java:320) [org.apache.sling.scripting.javascript:3.1.4]
	at org.apache.sling.scripting.javascript.internal.RhinoJavaScriptEngine.eval(RhinoJavaScriptEngine.java:155) [org.apache.sling.scripting.javascript:3.1.4]
	at org.apache.sling.scripting.api.AbstractSlingScriptEngine.eval(AbstractSlingScriptEngine.java:44) [org.apache.sling.scripting.api:2.2.0]
	at java.scripting/javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:231)
	at io.uhndata.cards.forms.internal.ExpressionUtilsImpl.toJavaScriptObject(ExpressionUtilsImpl.java:79) [io.uhndata.cards.data-model-forms-impl:0.9.36.SNAPSHOT]
	at io.uhndata.cards.forms.internal.ExpressionUtilsImpl.lambda$evaluate$0(ExpressionUtilsImpl.java:104) [io.uhndata.cards.data-model-forms-impl:0.9.36.SNAPSHOT]
	at java.base/java.util.HashMap.forEach(HashMap.java:1429)
	at io.uhndata.cards.forms.internal.ExpressionUtilsImpl.evaluate(ExpressionUtilsImpl.java:103) [io.uhndata.cards.data-model-forms-impl:0.9.36.SNAPSHOT]
	at io.uhndata.cards.forms.internal.ComputedAnswersEditor.computeAnswer(ComputedAnswersEditor.java:183) [io.uhndata.cards.data-model-forms-impl:0.9.36.SNAPSHOT]
	at io.uhndata.cards.forms.internal.ComputedAnswersEditor.lambda$handleLeave$3(ComputedAnswersEditor.java:169) [io.uhndata.cards.data-model-forms-impl:0.9.36.SNAPSHOT]
	...

05.01.2026 14:30:04.127 *ERROR* [127.0.0.1 [1767641403924] POST /Forms/cbae45fb-e7b0-4493-a2ce-f30844f2b3c4 HTTP/1.1] io.uhndata.cards.forms.internal.ExpressionUtilsImpl Could not parse Long from class org.mozilla.javascript.NativeNumber
05.01.2026 14:30:04.128 *ERROR* [127.0.0.1 [1767641403924] POST /Forms/cbae45fb-e7b0-4493-a2ce-f30844f2b3c4 HTTP/1.1] io.uhndata.cards.forms.internal.ExpressionUtilsImpl Could not parse Long from class org.mozilla.javascript.NativeNumber
05.01.2026 14:30:04.132 *ERROR* [127.0.0.1 [1767641403924] POST /Forms/cbae45fb-e7b0-4493-a2ce-f30844f2b3c4 HTTP/1.1] io.uhndata.cards.forms.internal.ExpressionUtilsImpl Could not parse Long from class org.mozilla.javascript.NativeNumber

[veronikaslc]

ReadME file prereqs has to be adjusted: Java and Maven versions

[acrowthe]

Looks good. Tested:

• Docker builds
• Your Experience Inpatient patient portal
• Data import
• Emails
• Backend computed questions (including additional tests from #2200)
• Locking
• Vocabularies