SPIGOT-7946: API for server pause when empty seconds

By: md_5 <git@md-5.net>

paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -2292,6 +2292,16 @@ public final class CraftServer implements Server {
         return console.getPlayerIdleTimeout();
     }
 
+    @Override
+    public int getPauseWhenEmptyTime() {
+        return this.getProperties().pauseWhenEmptySeconds;
+    }
+
+    @Override
+    public void setPauseWhenEmptyTime(int seconds) {
+        this.getProperties().pauseWhenEmptySeconds = seconds;
+    }
+
     @Override
     public ChunkGenerator.ChunkData createChunkData(World world) {
         Preconditions.checkArgument(world != null, "World cannot be null");