Clean up field presence checks and tests in anticipation of Protobuf Editions

fdb-record-layer-core/src/main/java/com/apple/foundationdb/record/metadata/MetaDataEvolutionValidator.java

@@ -274,13 +274,12 @@ private void validateField(@Nonnull FieldDescriptor oldFieldDescriptor, @Nonnull
         if (oldFieldDescriptor.isRequired() && !newFieldDescriptor.isRequired()) {
             throw new MetaDataException("required field is no longer required",
                     LogMessageKeys.FIELD_NAME, oldFieldDescriptor.getName());
-        } else if (oldFieldDescriptor.isOptional() && !newFieldDescriptor.isOptional()) {
-            // TODO: In theory, optional -> repeated is okay, but only if the field is not indexed
-            throw new MetaDataException("optional field is no longer optional",
-                    LogMessageKeys.FIELD_NAME, oldFieldDescriptor.getName());
         } else if (oldFieldDescriptor.isRepeated() && !newFieldDescriptor.isRepeated()) {
             throw new MetaDataException("repeated field is no longer repeated",
                     LogMessageKeys.FIELD_NAME, oldFieldDescriptor.getName());
+        } else if (oldFieldDescriptor.hasPresence() != newFieldDescriptor.hasPresence()) {
+            throw new MetaDataException("field changed whether default values are stored if set explicitly",
+                    LogMessageKeys.FIELD_NAME, oldFieldDescriptor.getName());
         }
         if (oldFieldDescriptor.getType().equals(FieldDescriptor.Type.ENUM)) {
             validateEnum(newFieldDescriptor.getName(), oldFieldDescriptor.getEnumType(), newFieldDescriptor.getEnumType());

fdb-record-layer-core/src/test/java/com/apple/foundationdb/record/metadata/MetaDataEvolutionValidatorTest.java

@@ -857,12 +857,17 @@ public void fieldLabelChanged() {
                 DescriptorProtos.FieldDescriptorProto.Label.LABEL_REQUIRED
         );
         for (int i = 0; i < labels.size(); i++) {
-            final int itr = i;
-            final DescriptorProtos.FieldDescriptorProto.Label label = labels.get(itr);
-            final String labelText = label.name().substring(label.name().indexOf('_') + 1).toLowerCase(Locale.ROOT);
-            final String errMsg = labelText + " field is no longer " + labelText;
+            final DescriptorProtos.FieldDescriptorProto.Label label = labels.get(i);
+            final String errMsg;
+            if (label == DescriptorProtos.FieldDescriptorProto.Label.LABEL_OPTIONAL) {
+                errMsg = "field changed whether default values are stored if set explicitly";
+            } else {
+                final String labelText = label.name().substring(label.name().indexOf('_') + 1).toLowerCase(Locale.ROOT);
+                errMsg = labelText + " field is no longer " + labelText;
+            }
+            final DescriptorProtos.FieldDescriptorProto.Label newLabel = labels.get((i + 1) % labels.size());
             FileDescriptor updatedFile = mutateField("MySimpleRecord", "str_value_indexed", oldFile,
-                    field -> field.setLabel(labels.get((itr + 1) % labels.size())));
+                    field -> field.setLabel(newLabel));
             assertInvalid(errMsg, oldFile, updatedFile);
 
             oldFile = updatedFile;

fdb-record-layer-core/src/test/java/com/apple/foundationdb/record/provider/foundationdb/query/FDBRecordStoreNullQueryTest.java

@@ -25,6 +25,7 @@
 import com.apple.foundationdb.record.RecordMetaDataBuilder;
 import com.apple.foundationdb.record.TestRecordsNulls2Proto;
 import com.apple.foundationdb.record.TestRecordsNulls3Proto;
+import com.apple.foundationdb.record.TestRecordsNulls3ExplicitProto;
 import com.apple.foundationdb.record.TestRecordsTupleFieldsProto;
 import com.apple.foundationdb.record.TupleFieldsProto;
 import com.apple.foundationdb.record.metadata.Key;
@@ -108,6 +109,10 @@
         return metaData.getRecordMetaData();
     }
 
+    protected static RecordMetaData proto3ExplicitMetaData() {
+        return RecordMetaData.newBuilder().setRecords(TestRecordsNulls3ExplicitProto.getDescriptor()).getRecordMetaData();
+    }
+
     @FunctionalInterface
     interface RecordBuilder<M extends Message> {
         M build(@Nonnull String name, @Nullable Integer intValue, @Nullable String stringValue);
@@ -175,6 +180,18 @@
         return builder.build();
     }
 
+    protected static TestRecordsNulls3ExplicitProto.MyNullRecord buildRecord3Explicit(@Nonnull String name, @Nullable Integer intValue, @Nullable String stringValue) {
+        TestRecordsNulls3ExplicitProto.MyNullRecord.Builder builder = TestRecordsNulls3ExplicitProto.MyNullRecord.newBuilder();
+        builder.setName(name);
+        if (intValue != null) {
+            builder.setIntValue(intValue);
+        }
+        if (stringValue != null) {
+            builder.setStringValue(stringValue);
+        }
+        return builder.build();
+    }
+
     protected <M extends Message> void saveTestRecords(@Nonnull RecordBuilder<M> builder) {
         recordStore.saveRecord(builder.build("empty", null, null));
         recordStore.saveRecord(builder.build("default", 0, ""));
@@ -365,6 +382,53 @@
         }
     }
 
+    // Explicit presence ("optional") correctly distguishes as well (results same as proto2).
+    @Test
+    public void testProto3Explicit() {
+        try (FDBRecordContext context = openContext()) {
+            createOrOpenRecordStore(context, proto3ExplicitMetaData());
+            saveTestRecords(FDBRecordStoreNullQueryTest::buildRecord3Explicit);
+
+            assertThat(executeQuery(RecordQuery.newBuilder()
+                            .setRecordType("MyNullRecord")
+                            .setFilter(Query.field("int_value").equalsValue(2))
+                            .build()),
+                    is(Collections.singletonList("two")));
+            assertThat(executeQuery(RecordQuery.newBuilder()
+                            .setRecordType("MyNullRecord")
+                            .setFilter(Query.field("string_value").equalsValue("B"))
+                            .build()),
+                    is(Collections.singletonList("two")));
+
+            assertThat(executeQuery(RecordQuery.newBuilder()
+                    .setRecordType("MyNullRecord")
+                    .setFilter(Query.field("int_value").isNull())
+                    .build()),
+                    is(Collections.singletonList("empty")));
+            assertThat(executeQuery(RecordQuery.newBuilder()
+                    .setRecordType("MyNullRecord")
+                    .setFilter(Query.field("int_value").equalsValue(0))
+                    .build()),
+                    is(Collections.singletonList("default")));
+            assertThat(executeQuery(RecordQuery.newBuilder()
+                            .setRecordType("MyNullRecord")
+                            .setFilter(Query.field("string_value").isNull())
+                            .build()),
+                    is(Collections.singletonList("empty")));
+            assertThat(executeQuery(RecordQuery.newBuilder()
+                            .setRecordType("MyNullRecord")
+                            .setFilter(Query.field("string_value").equalsValue(""))
+                            .build()),
+                    is(Collections.singletonList("default")));
+
+            assertThat(executeQuery(RecordQuery.newBuilder()
+                    .setRecordType("MyNullRecord")
+                    .setSort(Key.Expressions.field("int_value"))
+                    .build()),
+                    is(Arrays.asList("empty", "minus", "default", "one", "two")));
+        }
+    }
+
     @Test
     public void testCompareSerialization() throws Exception {
         final TestRecordsNulls2Proto.MyNullRecord emptyProto2 = buildRecord2("record", null, null);

fdb-record-layer-core/src/test/proto/test_records_nulls_3.proto

@@ -1,3 +1,22 @@
+/*
+ * test_records_nulls_3.proto
+ *
+ * This source file is part of the FoundationDB open source project
+ *
+ * Copyright 2015-2018 Apple Inc. and the FoundationDB project authors
+ *
+ * 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.
+ */
 syntax = "proto3";
 
 package com.apple.foundationdb.record.testnulls3;

fdb-record-layer-core/src/test/proto/test_records_nulls_3_explicit.proto

@@ -0,0 +1,37 @@
+/*
+ * test_records_nulls_3_explicit.proto
+ *
+ * This source file is part of the FoundationDB open source project
+ *
+ * Copyright 2026 Apple Inc. and the FoundationDB project authors
+ *
+ * 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.
+ */
+syntax = "proto3";
+
+package com.apple.foundationdb.record.testnulls3explicit;
+
+option java_package = "com.apple.foundationdb.record";
+option java_outer_classname = "TestRecordsNulls3ExplicitProto";
+
+import "record_metadata_options.proto";
+
+message MyNullRecord {
+  optional string name = 1 [(field).primary_key = true];
+  optional string string_value = 2 [(field).index = {}];
+  optional int32 int_value = 3 [(field).index = {}];
+}
+
+message RecordTypeUnion {
+  optional MyNullRecord _MyNullRecord = 1;
+}