The JCK test throw java.lang.NullPointerException.
The test passed with JDK-8363972 changes backed out.

$ $STABLE_JAVA/bin/java -jar ${JCK_EXTRA_HOME}/jck4jdk.jar -jck:${JCK_RUNTIME_HOME} -testjdk:${TESTED_JAVA} -workDir:results -extra:${JCK_EXTRA_HOME} -concurrency 1 -verbose -vmoptions:"-Xint" api/java_text/DecimalFormatSymbols/serial/InputTests.html
[jck4jdk] Using Extra: /scratch/kvn/JCK26/JCK-extra-26/binaries/linux-amd64/config/runtime-multiJVMgroup-noagent-Linux.jti
[jck4jdk] Using JCK: /scratch/kvn/JCK26/JCK-runtime-26
Aug 28, 2025, 4:03:27 PM Harness starting test run with configuration "jck_runtime_linux"...
FAILED: api/java_text/DecimalFormatSymbols/serial/InputTests.html (test cases: 1; all failed; first test case failure: InputTest0001)
Aug 28, 2025, 4:03:33 PM Finished executing all tests, wait for cleanup...
Aug 28, 2025, 4:03:33 PM Harness done with cleanup from test run.
Total time: 5 seconds
Setup time: 0 seconds
Cleanup time: 0 seconds
Tests found in the suite: 123,441
Test results: failed: 1

Results written to /scratch/kvn/JCK26/results
Error: Some tests did not pass

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From test output:

java.lang.NullPointerException: Cannot invoke "java.util.Locale.getUnicodeLocaleType(String)" because "locale" is null
        at java.base/java.text.DecimalFormatSymbols.loadNumberData(DecimalFormatSymbols.java:867)
        at java.base/java.text.DecimalFormatSymbols.readObject(DecimalFormatSymbols.java:1018)