Add support for Player#getPing in Spigot

Affects issues:
- Fixed #3140

Plan/bukkit/src/main/java/com/djrapitops/plan/gathering/timed/BukkitPingCounter.java

@@ -100,6 +100,7 @@ public class BukkitPingCounter extends TaskSystem.Task implements Listener {
 
     private Optional<PingMethod> loadPingMethod() {
         PingMethod[] methods = new PingMethod[]{
+                new SpigotPingMethod(),
                 new PaperPingMethod(),
                 new ReflectiveLatencyFieldMethod(),
                 new ReflectivePingFieldMethod(),

Plan/bukkit/src/main/java/com/djrapitops/plan/gathering/timed/SpigotPingMethod.java

@@ -0,0 +1,64 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016-2018
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.djrapitops.plan.gathering.timed;
+
+import org.bukkit.entity.Player;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+public class SpigotPingMethod implements PingMethod {
+
+    private String reasonForUnavailability;
+
+    @Override
+    public boolean isAvailable() {
+        try {
+            //Only available in Paper
+            Class.forName("org.bukkit.entity.Player").getDeclaredMethod("getPing");
+            return true;
+        } catch (ClassNotFoundException | NoSuchMethodException noSuchMethodEx) {
+            reasonForUnavailability = noSuchMethodEx.toString();
+            return false;
+        }
+    }
+
+    @Override
+    public int getPing(Player player) {
+        if (!reasonForUnavailability.isEmpty()) return -1;
+
+        try {
+            Method getPing = player.getClass().getDeclaredMethod("getPing");
+            return (int) getPing.invoke(player);
+        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
+            reasonForUnavailability = e.toString();
+            return -1;
+        }
+    }
+
+    @Override
+    public String getReasonForUnavailability() {
+        return reasonForUnavailability;
+    }
+}