fix error being thrown getServerFor in Bungeecord/Velocity in the api c…

…loses #64

when plugins messing around with proxy internals (eg: limboapi) the field server in redis data of the player set to null which can become problematic for velocity due checking of null in velocity but i applied the same stuff to the bungeecord version aswell and document it in the javadocs

RedisBungee-API/src/main/java/com/imaginarycode/minecraft/redisbungee/AbstractRedisBungeeAPI.java

@@ -20,6 +20,7 @@
 import com.imaginarycode.minecraft.redisbungee.api.summoners.JedisPooledSummoner;
 import com.imaginarycode.minecraft.redisbungee.api.summoners.Summoner;
 import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import redis.clients.jedis.Jedis;
 import redis.clients.jedis.JedisCluster;
 import redis.clients.jedis.JedisPool;
@@ -81,8 +82,9 @@ public final long getLastOnline(@NonNull UUID player) {
      * as well, and will return local information on them.
      *
      * @param player a player uuid
-     * @return a String name for the server the player is on.
+     * @return a String name for the server the player is on. Can be Null if plugins is doing weird stuff to the proxy internals
      */
+    @Nullable
     public final String getServerNameFor(@NonNull UUID player) {
         return plugin.getDataManager().getServer(player);
     }

RedisBungee-Bungee/src/main/java/com/imaginarycode/minecraft/redisbungee/RedisBungeeAPI.java

@@ -14,6 +14,7 @@
 import net.md_5.bungee.api.config.ServerInfo;
 import net.md_5.bungee.api.plugin.Plugin;
 import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.UUID;
 
@@ -43,8 +44,11 @@ public RedisBungeeAPI(RedisBungeePlugin<?> plugin) {
      * @return {@link ServerInfo} Can be null if proxy can't find it.
      * @see #getServerNameFor(UUID)
      */
+    @Nullable
     public final ServerInfo getServerFor(@NonNull UUID player) {
-        return ((Plugin) this.plugin).getProxy().getServerInfo(this.getServerNameFor(player));
+        String serverName = this.getServerNameFor(player);
+        if (serverName == null) return null;
+        return ((Plugin) this.plugin).getProxy().getServerInfo(serverName);
     }
 
     /**

RedisBungee-Velocity/src/main/java/com/imaginarycode/minecraft/redisbungee/RedisBungeeAPI.java

@@ -14,6 +14,7 @@
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.proxy.server.ServerInfo;
 import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.UUID;
 
@@ -44,8 +45,11 @@ public RedisBungeeAPI(RedisBungeePlugin<?> plugin) {
      * @return {@link ServerInfo} Can be null if proxy can't find it.
      * @see #getServerNameFor(UUID)
      */
+    @Nullable
     public final ServerInfo getServerFor(@NonNull UUID player) {
-        return ((RedisBungeeVelocityPlugin) this.plugin).getProxy().getServer(this.getServerNameFor(player)).map((RegisteredServer::getServerInfo)).orElse(null);
+        String serverName = this.getServerNameFor(player);
+        if (serverName == null) return null;
+        return ((RedisBungeeVelocityPlugin) this.plugin).getProxy().getServer(serverName).map((RegisteredServer::getServerInfo)).orElse(null);
     }
 
     /**