use exclusive fromSequenceNumber in eventsByTag, #22145

* The reason is to have a consistent approach for Sequence and
  TimeBasedUUID, which are both intended as unique event identifiers.
* This means that you can use the offset that is returned in `EventEnvelope`
  as the `offset` parameter in a subsequent query.

akka-docs/rst/java/code/docs/persistence/PersistenceQueryDocTest.java

@@ -101,6 +101,17 @@ public class PersistenceQueryDocTest {
               TimeUnit.MILLISECONDS), TimeUnit.MILLISECONDS);
     }
 
+    /**
+     * You can use `NoOffset` to retrieve all events with a given tag or retrieve a subset of all
+     * events by specifying a `Sequence` `offset`. The `offset` corresponds to an ordered sequence number for
+     * the specific tag. Note that the corresponding offset of each event is provided in the
+     * [[akka.persistence.query.EventEnvelope]], which makes it possible to resume the
+     * stream at a later point from a given offset.
+     *
+     * The `offset` is exclusive, i.e. the event with the exact same sequence number will not be included
+     * in the returned stream. This means that you can use the offset that is returned in `EventEnvelope`
+     * as the `offset` parameter in a subsequent query.
+     */
     @Override
     public Source<EventEnvelope, NotUsed> eventsByTag(String tag, Offset offset) {
       if(offset instanceof Sequence){
@@ -108,7 +119,8 @@ public class PersistenceQueryDocTest {
         final Props props = MyEventsByTagPublisher.props(tag, sequenceOffset.value(), refreshInterval);
         return Source.<EventEnvelope>actorPublisher(props).
           mapMaterializedValue(m -> NotUsed.getInstance());
-      }
+      } else if (offset == NoOffset.getInstance())
+        return eventsByTag(tag, Offset.sequence(0L)); //recursive
       else
         throw new IllegalArgumentException("MyJavadslReadJournal does not support " + offset.getClass().getName() + " offsets");
     }

akka-docs/rst/java/code/docs/persistence/query/MyEventsByTagJavaPublisher.java

@@ -84,7 +84,7 @@ class MyEventsByTagJavaPublisher extends AbstractActorPublisher<EventEnvelope> {
   private void query() {
     if (buf.isEmpty()) {
       final String query = "SELECT id, persistent_repr " +
-        "FROM journal WHERE tag = ? AND id >= ? " +
+        "FROM journal WHERE tag = ? AND id > ? " +
         "ORDER BY id LIMIT ?";
 
       try (PreparedStatement s = connection.prepareStatement(query)) {