start converting from bukkit to hytale

src/main/java/at/helpch/placeholderapi/expansion/Relational.java

@@ -0,0 +1,43 @@
+/*
+ * This file is part of PlaceholderAPI
+ *
+ * PlaceholderAPI
+ * Copyright (c) 2015 - 2026 PlaceholderAPI Team
+ *
+ * PlaceholderAPI free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PlaceholderAPI is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package at.helpch.placeholderapi.expansion;
+
+import org.bukkit.entity.Player;
+
+/**
+ * Implementing this interface allows your {@link at.helpch.placeholderapi.expansion.PlaceholderExpansion PlaceholderExpansion}
+ * to be used as a relational placeholder expansion.
+ *
+ * <p>Relational placeholders take two Players as input and are always prefixed with {@code rel_},
+ * so {@code %foo_bar%} becomes {@code %rel_foo_bar%}
+ */
+public interface Relational {
+
+    /**
+     * This method is called whenever a placeholder starting with {@code rel_} is called.
+     *
+     * @param one        The first player used for the placeholder.
+     * @param two        The second player used for the placeholder.
+     * @param identifier The text right after the expansion's name (%expansion_<b>identifier</b>%)
+     * @return Parsed String from the expansion.
+     */
+    String onPlaceholderRequest(Player one, Player two, String identifier);
+}