add code

src/main/java/sh/okx/rankup/ranks/requirements/Requirement.java

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+package sh.okx.rankup.ranks.requirements;
+
+import lombok.Getter;
+import lombok.Setter;
+import org.bukkit.entity.Player;
+import sh.okx.rankup.Rankup;
+
+public abstract class Requirement implements Cloneable {
+  protected Rankup plugin;
+  @Getter
+  protected String name;
+  @Getter
+  @Setter
+  protected double amount;
+
+  public Requirement(Rankup plugin, String name) {
+    this.plugin = plugin;
+    this.name = name;
+  }
+
+  protected Requirement(Requirement clone) {
+    if(clone != null) {
+      this.plugin = clone.plugin;
+      this.name = clone.name;
+      this.amount = clone.amount;
+    }
+  }
+
+  /**
+   * Check if a player meets this requirement
+   * @param player the player to check
+   * @return true if they meet the requirement, false otherwise
+   */
+  public abstract boolean check(Player player);
+
+  /**
+   * Apply the effect of this requirement to the player.
+   * For money, this could be taking money away from the player.
+   * You can assume that <code>Requirement#check(Player)</code> has been called,
+   * and has returned true immediately prior to this.
+   * @param player the player to take from
+   */
+  public abstract void apply(Player player);
+
+  /**
+   * Get the remaining amount needed for <code>Requirement#check(Player)</code> to yield true.
+   * This is not required and is only used in placeholders.
+   * @param player the player to find the remaining amount of
+   * @return the remaining amount needed. Should be non-negative.
+   */
+  public double getRemaining(Player player) {
+    return amount;
+  }
+  public abstract Requirement clone();
+}