Add API bulk user lookup method (#4285)

api/src/main/java/net/luckperms/api/model/user/UserManager.java

@@ -81,6 +81,15 @@ public interface UserManager {
         return loadUser(uniqueId, null);
     }
 
+    /**
+     * Loads multiple users from the plugin's storage provider into memory.
+     *
+     * @param uniqueIds the uuids of the users to load
+     * @return a future for an unmodifiable map of loaded users
+     * @throws NullPointerException if the uuid set is null
+     */
+    @NonNull CompletableFuture<@Unmodifiable Map<UUID, User>> loadUsers(@NonNull Set<@NonNull UUID> uniqueIds);
+
     /**
      * Uses the LuckPerms cache to find a uuid for the given username.
      *

common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiUserManager.java

@@ -49,6 +49,7 @@ import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
 
 public class ApiUserManager extends ApiAbstractManager<User, net.luckperms.api.model.user.User, UserManager<?>> implements net.luckperms.api.model.user.UserManager {
     public ApiUserManager(LuckPermsPlugin plugin, UserManager<?> handle) {
@@ -76,6 +77,18 @@ public class ApiUserManager extends ApiAbstractManager<User, net.luckperms.api.m
                 .thenApply(this::proxyAndRegisterUsage);
     }
 
+    @Override
+    public @NonNull CompletableFuture<Map<UUID, net.luckperms.api.model.user.User>> loadUsers(@NonNull Set<@NonNull UUID> uniqueIds) {
+        Objects.requireNonNull(uniqueIds, "uuid set");
+
+        if (uniqueIds.isEmpty()) {
+            return CompletableFuture.completedFuture(Map.of());
+        }
+
+        return this.plugin.getStorage().loadUsers(uniqueIds)
+                .thenApply(map -> map.entrySet().stream().collect(Collectors.toUnmodifiableMap(Map.Entry::getKey, entry -> this.proxyAndRegisterUsage(entry.getValue()))));
+    }
+
     @Override
     public @NonNull CompletableFuture<UUID> lookupUniqueId(@NonNull String username) {
         Objects.requireNonNull(username, "username");