Merge branch '103-shared-global-ids-annotation' into dev

Author: greenrobot-team

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

@@ -14,4 +14,18 @@
 @Retention(RetentionPolicy.CLASS)
 @Target(ElementType.TYPE)
 public @interface Sync {
+
+    /**
+     * Set to {@code true} to enable shared global IDs for a {@link Sync}-enabled {@link Entity} class.
+     * <p>
+     * By default each Sync client has its own local {@link Id ID} space for Objects.
+     * IDs are mapped to global IDs when syncing behind the scenes. Turn this on
+     * to treat Object IDs as global and turn of ID mapping. The ID of an Object will
+     * then be the same on all clients.
+     * <p>
+     * When using this, it is recommended to use {@link Id#assignable() assignable IDs}
+     * to turn off automatically assigned IDs. Without special care, two Sync clients are
+     * likely to overwrite each others Objects if IDs are assigned automatically.
+     */
+    boolean sharedGlobalIds() default false;
 }