feat(board): generate physical oak quest boards

src/main/java/games/dmg/spigotquestboard/BoardRegistry.java

@@ -1,6 +1,7 @@
 package games.dmg.spigotquestboard;
 
 import java.io.IOException;
+import java.util.Collection;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Objects;
@@ -16,12 +17,22 @@ final class BoardRegistry {
     }
 
     synchronized BoardRegistrationResult register(RegisteredBoard board) throws IOException {
-        Objects.requireNonNull(board, "board");
-        if (boards.containsKey(board.id())) {
-            return BoardRegistrationResult.ALREADY_REGISTERED;
-        }
+        return registerAll(Set.of(Objects.requireNonNull(board, "board")));
+    }
+
+    synchronized BoardRegistrationResult registerAll(Collection<RegisteredBoard> additions)
+        throws IOException {
+        Objects.requireNonNull(additions, "additions");
         Map<BoardId, RegisteredBoard> candidate = new LinkedHashMap<>(boards);
-        candidate.put(board.id(), board);
+        for (RegisteredBoard board : additions) {
+            Objects.requireNonNull(board, "board");
+            if (candidate.putIfAbsent(board.id(), board) != null) {
+                return BoardRegistrationResult.ALREADY_REGISTERED;
+            }
+        }
+        if (additions.isEmpty()) {
+            return BoardRegistrationResult.CREATED;
+        }
         repository.save(new BoardState(Set.copyOf(candidate.values())));
         boards = Map.copyOf(candidate);
         return BoardRegistrationResult.CREATED;