java-api: add SyncClock and SyncPrecedence annotations

Author: greenrobot-team

objectbox-java-api/src/main/java/io/objectbox/annotation/SyncClock.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright © 2026 ObjectBox Ltd. <https://objectbox.io>
+ *
+ * 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 io.objectbox.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a {@code long} (64-bit integer) field of a {@link Sync}-enabled {@link Entity} class as the sync clock, a
+ * "hybrid logical clock" to resolve Sync conflicts.
+ * <p>
+ * These clock values allow "last write wins" conflict resolution.
+ * <p>
+ * There can be only one sync clock per sync entity type; which is also recommended for basic conflict resolution.
+ * <p>
+ * For new objects, initialize the property value to {@code 0} to reserve "a slot" in the object data. ObjectBox Sync
+ * will update this property automatically on put operations.
+ * <p>
+ * As a hybrid clock, it combines a wall clock with a logical counter to compensate for some clock skew effects.
+ */
+@Retention(RetentionPolicy.CLASS)
+@Target(ElementType.FIELD)
+public @interface SyncClock {
+}

objectbox-java-api/src/main/java/io/objectbox/annotation/SyncPrecedence.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright © 2026 ObjectBox Ltd. <https://objectbox.io>
+ *
+ * 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 io.objectbox.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a {@code long} (64-bit integer) field of a {@link Sync}-enabled {@link Entity} class as the "sync precedence"
+ * to customize Sync conflict resolution.
+ * <p>
+ * Developer-assigned precedence values are then used to resolve conflicts via "higher precedence wins". Defining and
+ * assigning precedence values are completely in the hands of the developer (the ObjectBox user).
+ * <p>
+ * There can be only one sync precedence per sync entity type.
+ * <p>
+ * Typically, it is combined with a {@link SyncClock}, with the latter being the tie-breaker for equal precedence
+ * values.
+ */
+@Retention(RetentionPolicy.CLASS)
+@Target(ElementType.FIELD)
+public @interface SyncPrecedence {
+}