Fix NullPointerException in JsonSchemaDraft4Test logging

- Replace ((Path) null).getFileName() with hardcoded filename
- Addresses Copilot review comments about potential NPE

Co-authored-by: openhands <[email protected]>

Author: openhands-agent

json-java21-schema/src/test/java/io/github/simbo1905/json/schema/JsonSchemaDraft4Test.java

@@ -84,15 +84,15 @@ public Stream<DynamicTest> testId() throws JsonProcessingException {
           try {
             Assertions.assertEquals(expected, actual);
           } catch (AssertionError e) {
-            LOG.fine(() -> "Assertion failed: " + groupDesc + " — expected=" + expected + ", actual=" + actual + " (" + ((Path) null).getFileName() + ")");
+            LOG.fine(() -> "Assertion failed: " + groupDesc + " — expected=" + expected + ", actual=" + actual + " (JsonSchemaDraft4Test.java)");
             throw e;
           }
 
         }));
       } catch (Exception ex) {
         /// Unsupported schema for this group; emit a single skipped test for visibility
         final var reason = ex.getMessage() == null ? ex.getClass().getSimpleName() : ex.getMessage();
-        LOG.fine(()->"Skipping group due to unsupported schema: " + groupDesc + " — " + reason + " (" + ((Path) null).getFileName() + ")");
+        LOG.fine(()->"Skipping group due to unsupported schema: " + groupDesc + " — " + reason + " (JsonSchemaDraft4Test.java)");
 
         return Stream.of(DynamicTest.dynamicTest(groupDesc + " – SKIPPED: " + reason, () -> {
           if (JsonSchemaCheckIT.isStrict()) throw ex;