Introduce a fluent connection request API.

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

@@ -0,0 +1,84 @@
+package com.velocitypowered.api.proxy;
+
+import com.velocitypowered.api.server.ServerInfo;
+import net.kyori.text.Component;
+
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Represents a connection request. A connection request is created using {@link Player#createConnectionRequest(ServerInfo)}
+ * and is used to allow a plugin to compose and request a connection to another Minecraft server using a fluent API.
+ */
+public interface ConnectionRequestBuilder {
+    /**
+     * Returns the server that this connection request represents.
+     * @return the server this request will connect to
+     */
+    ServerInfo getServer();
+
+    /**
+     * Initiates the connection to the remote server and emits a result on the {@link CompletableFuture} after the user
+     * has logged on. No messages will be communicated to the client: the user is responsible for all error handling.
+     * @return a {@link CompletableFuture} representing the status of this connection
+     */
+    CompletableFuture<Result> connect();
+
+    /**
+     * Initiates the connection to the remote server without waiting for a result. Velocity will use generic error
+     * handling code to notify the user.
+     */
+    void fireAndForget();
+
+    /**
+     * Represents the result of a connection request.
+     */
+    interface Result {
+        /**
+         * Determines whether or not the connection request was successful.
+         * @return whether or not the request succeeded
+         */
+        default boolean isSuccessful() {
+            return getStatus() == Status.SUCCESS;
+        }
+
+        /**
+         * Returns the status associated with this result.
+         * @return the status for this result
+         */
+        Status getStatus();
+
+        /**
+         * Returns a reason for the failure to connect to the server. None may be provided.
+         * @return the reason why the user could not connect to the server
+         */
+        Optional<Component> getReason();
+    }
+
+    /**
+     * Represents the status of a connection request initiated by a {@link ConnectionRequestBuilder}.
+     */
+    enum Status {
+        /**
+         * The player was successfully connected to the server.
+         */
+        SUCCESS,
+        /**
+         * The player is already connected to this server.
+         */
+        ALREADY_CONNECTED,
+        /**
+         * The connection is already in progress.
+         */
+        CONNECTION_IN_PROGRESS,
+        /**
+         * A plugin has cancelled this connection.
+         */
+        CONNECTION_CANCELLED,
+        /**
+         * The server disconnected the user. A reason may be provided in the {@link Result} object.
+         */
+        SERVER_DISCONNECTED
+    }
+
+}

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

@@ -57,4 +57,11 @@ public interface Player {
      * @param position the position for the message
      */
     void sendMessage(@Nonnull Component component, @Nonnull MessagePosition position);
+
+    /**
+     * Creates a new connection request so that the player can connect to another server.
+     * @param info the server to connect to
+     * @return a new connection request
+     */
+    ConnectionRequestBuilder createConnectionRequest(@Nonnull ServerInfo info);
 }