Add server registration API.

api/src/main/java/com/velocitypowered/api/proxy/ProxyServer.java

@@ -1,5 +1,7 @@
 package com.velocitypowered.api.proxy;
 
+import com.velocitypowered.api.server.ServerInfo;
+
 import javax.annotation.Nonnull;
 import java.util.Collection;
 import java.util.Optional;
@@ -29,4 +31,29 @@ public interface ProxyServer {
      * @return the players online on this proxy
      */
     Collection<Player> getAllPlayers();
+
+    /**
+     * Retrieves a registered {@link ServerInfo} instance by its name.
+     * @param name the name of the server
+     * @return the server
+     */
+    Optional<ServerInfo> getServerInfo(@Nonnull String name);
+
+    /**
+     * Retrieves all {@link ServerInfo}s registered with this proxy.
+     * @return the servers registered with this proxy
+     */
+    Collection<ServerInfo> getAllServers();
+
+    /**
+     * Registers a server with this proxy. A server with this name should not already exist.
+     * @param server the server to register
+     */
+    void registerServer(@Nonnull ServerInfo server);
+
+    /**
+     * Unregisters this server from the proxy.
+     * @param server the server to unregister
+     */
+    void unregisterServer(@Nonnull ServerInfo server);
 }