CBL-8389 : Fix build and static analysis issues in kt-serialization API changes (#498)

* Replace var with explicit FLDict type in Document.setContent (common is compiled at Java 8)
* Suppress PMD SingularField and SpotBugs URF_UNREAD_FIELD on Document.extraBackingStore (keep-alive field)
* Add null check on FLValue.fromData() result in Document.setContent (NP_NULL_ON_SOME_PATH)
* Move serialization tests from test/java to test/kotlin so that only the android-ktx test builds compile them :
    - FleeceSerializationTest.kt moved as-is
    - ResultTest.kt renamed to ResultSerializationTest.kt
    - Serialization test and TestModel extracted from CollectionTest.kt into new CollectionSerializationTest.kt

Author: pasin

common/main/java/com/couchbase/lite/Document.java

@@ -136,6 +136,8 @@ static Document getDocumentWithRevisions(@NonNull Collection collection, @NonNul
 
     // Set by setData(FLSliceResult,boolean) to keep the Fleece backing store from being GC'd.
     // (This is kind of a hack, and it's only used ephemerally by Kotlin serialization.)
+    @SuppressFBWarnings("URF_UNREAD_FIELD")
+    @SuppressWarnings("PMD.SingularField")
     @GuardedBy("lock")
     @Nullable
     private FLSliceResult extraBackingStore;
@@ -632,9 +634,10 @@ private void setC4Document(@Nullable C4Document c4doc, boolean mutable) {
     // for use by CollectionExtensions.kt
     void setContent(@NonNull FLSliceResult fleeceData, boolean mutable) {
         synchronized (lock) {
-            var data = FLValue.fromData(fleeceData).asFLDict();
+            final FLValue body = FLValue.fromData(fleeceData);
+            if (body == null) { throw new CouchbaseLiteError("Failed parsing fleece data"); }
             extraBackingStore = fleeceData;
-            setContentLocked(data, mutable);
+            setContentLocked(body.asFLDict(), mutable);
         }
     }
 

common/test/java/com/couchbase/lite/CollectionTest.kt

@@ -17,8 +17,6 @@
 package com.couchbase.lite
 
 import com.couchbase.lite.internal.utils.SlowTest
-import kotlinx.serialization.Serializable
-import kotlinx.serialization.Transient
 import org.junit.Assert
 import org.junit.Test
 
@@ -1215,52 +1213,4 @@ class CollectionTest : BaseDbTest() {
 
         Assert.assertEquals(scope, testDatabase.getScope(Scope.DEFAULT_NAME))
     }
-
-    //---------------------------------------------
-    //  Model-based (serialization) API
-    //---------------------------------------------
-
-    @Test
-    fun saveNewDocInCollectionFromModel() {
-        val id = getUniqueName("test_doc")
-
-        // Create a new model and save it:
-        val model = TestModel("Nigel", 12)
-        testCollection.save(model, id)
-        Assert.assertEquals(testCollection, model.documentMeta?.collection)
-        Assert.assertEquals(id, model.documentMeta?.id)
-
-        // Read it back:
-        Assert.assertEquals(1, testCollection.count)
-        val gotModel = testCollection.getDocumentAs<TestModel>(id)!!
-        Assert.assertEquals(model, gotModel)
-
-        // Modify and save again:
-        gotModel.favorites = listOf("XTC", "Elvis Costello")
-        Assert.assertTrue(testCollection.save(gotModel))
-        Assert.assertNotEquals(model.documentMeta?.revisionID, gotModel.documentMeta?.revisionID)
-
-        // Get it as a regular Document and verify the contents:
-        val doc = testCollection.getDocument(id)!!
-        Assert.assertEquals(gotModel.documentMeta?.revisionID, doc.revisionID)
-        Assert.assertEquals("Nigel", doc.getString("name"))
-        Assert.assertEquals(12, doc.getInt("age"))
-        val faves = doc.getArray("favorites")!!
-        Assert.assertEquals(2, faves.count())
-        Assert.assertEquals("XTC", faves.getString(0))
-        Assert.assertEquals("Elvis Costello", faves.getString(1))
-
-        // Delete the model. `model` is out of date, so it will fail, but `gotModel` is OK:
-        Assert.assertFalse(testCollection.delete(model, ConcurrencyControl.FAIL_ON_CONFLICT))
-        Assert.assertTrue(testCollection.delete(gotModel, ConcurrencyControl.FAIL_ON_CONFLICT))
-    }
-}
-
-
-// Simple Model class for tests
-@Serializable
-data class TestModel(var name: String,
-                     var age: Int,
-                     var favorites: List<String>? = null): DocumentModel {
-    @Transient override var documentMeta: DocumentMeta? = null
 }

common/test/kotlin/com/couchbase/lite/CollectionSerializationTest.kt

@@ -0,0 +1,74 @@
+//
+// Copyright (c) 2026 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http:// www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package com.couchbase.lite
+
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
+import org.junit.Assert
+import org.junit.Test
+
+
+/** Tests serialization-based Collection accessors implemented in CollectionExtensions.kt. */
+class CollectionSerializationTest : BaseDbTest() {
+    //---------------------------------------------
+    //  Model-based (serialization) API
+    //---------------------------------------------
+
+    @Test
+    fun saveNewDocInCollectionFromModel() {
+        val id = getUniqueName("test_doc")
+
+        // Create a new model and save it:
+        val model = TestModel("Nigel", 12)
+        testCollection.save(model, id)
+        Assert.assertEquals(testCollection, model.documentMeta?.collection)
+        Assert.assertEquals(id, model.documentMeta?.id)
+
+        // Read it back:
+        Assert.assertEquals(1, testCollection.count)
+        val gotModel = testCollection.getDocumentAs<TestModel>(id)!!
+        Assert.assertEquals(model, gotModel)
+
+        // Modify and save again:
+        gotModel.favorites = listOf("XTC", "Elvis Costello")
+        Assert.assertTrue(testCollection.save(gotModel))
+        Assert.assertNotEquals(model.documentMeta?.revisionID, gotModel.documentMeta?.revisionID)
+
+        // Get it as a regular Document and verify the contents:
+        val doc = testCollection.getDocument(id)!!
+        Assert.assertEquals(gotModel.documentMeta?.revisionID, doc.revisionID)
+        Assert.assertEquals("Nigel", doc.getString("name"))
+        Assert.assertEquals(12, doc.getInt("age"))
+        val faves = doc.getArray("favorites")!!
+        Assert.assertEquals(2, faves.count())
+        Assert.assertEquals("XTC", faves.getString(0))
+        Assert.assertEquals("Elvis Costello", faves.getString(1))
+
+        // Delete the model. `model` is out of date, so it will fail, but `gotModel` is OK:
+        Assert.assertFalse(testCollection.delete(model, ConcurrencyControl.FAIL_ON_CONFLICT))
+        Assert.assertTrue(testCollection.delete(gotModel, ConcurrencyControl.FAIL_ON_CONFLICT))
+    }
+}
+
+
+// Simple Model class for tests
+@Serializable
+data class TestModel(var name: String,
+                     var age: Int,
+                     var favorites: List<String>? = null): DocumentModel {
+    @Transient override var documentMeta: DocumentMeta? = null
+}

…st/java/com/couchbase/lite/ResultTest.kt …ouchbase/lite/ResultSerializationTest.ktcommon/test/java/com/couchbase/lite/ResultTest.kt renamed to common/test/kotlin/com/couchbase/lite/ResultSerializationTest.kt common/test/java/com/couchbase/lite/ResultTest.kt renamed to common/test/kotlin/com/couchbase/lite/ResultSerializationTest.kt

@@ -67,4 +67,4 @@ class ResultSerializationTest : BaseQueryTest() {
 
         assertFalse(iter.hasNext())
     }
-}
+}