fix: generate Java enum arrays as lists

.github/workflows/ci.yml

@@ -24,5 +24,10 @@ jobs:
           distribution: 'temurin'
           java-version: '17'
 
+      - name: Test spec normalization
+        run: |
+          python3 -m pip install --quiet --break-system-packages pyyaml
+          python3 -m unittest discover -s scripts -p 'test_*.py'
+
       - name: Build
         run: mvn compile -q

scripts/normalize-spec-for-java.py

@@ -40,6 +40,12 @@ def collapse_unexpressible_unions(node, path, collapsed):
     if not isinstance(node, dict):
         return
 
+    items = node.get("items")
+    if node.get("uniqueItems") and isinstance(items, dict) and "enum" in items:
+        # native Java's Set<Enum> addItem helper constructs HashSet<String>.
+        # Use List<Enum>; the API still enforces uniqueness on the wire.
+        del node["uniqueItems"]
+
     for keyword in COMPOSED_KEYWORDS:
         branches = node.get(keyword)
         if not isinstance(branches, list):

scripts/test_normalize_spec_for_java.py

@@ -0,0 +1,27 @@
+import importlib.util
+import unittest
+from pathlib import Path
+
+spec = importlib.util.spec_from_file_location(
+    'normalize', Path(__file__).with_name('normalize-spec-for-java.py')
+)
+normalize = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(normalize)
+
+
+class EnumArrayTest(unittest.TestCase):
+    def test_enum_arrays_use_lists_without_losing_enum_values(self):
+        schema = {'type': 'array', 'uniqueItems': True,
+                  'items': {'type': 'string', 'enum': ['whatsapp', 'messenger']}}
+        normalize.collapse_unexpressible_unions(schema, '$', [])
+        self.assertNotIn('uniqueItems', schema)
+        self.assertEqual(schema['items']['enum'], ['whatsapp', 'messenger'])
+
+    def test_non_enum_arrays_keep_set_semantics(self):
+        schema = {'type': 'array', 'uniqueItems': True, 'items': {'type': 'string'}}
+        normalize.collapse_unexpressible_unions(schema, '$', [])
+        self.assertTrue(schema['uniqueItems'])
+
+
+if __name__ == '__main__':
+    unittest.main()