move force key checking into a system property (#736)

proxy/src/main/java/com/velocitypowered/proxy/VelocityServer.java

@@ -315,6 +315,9 @@ public class VelocityServer implements ProxyServer, ForwardingAudience {
       }
 
       commandManager.setAnnounceProxyCommands(configuration.isAnnounceProxyCommands());
+      if (System.getProperty("auth.forceSecureProfiles") == null) {
+        System.setProperty("auth.forceSecureProfiles", String.valueOf(configuration.isForceKeyAuthentication()));
+      }
     } catch (Exception e) {
       logger.error("Unable to read/load/save your velocity.toml. The server will shut down.", e);
       LogManager.shutdown();

proxy/src/main/java/com/velocitypowered/proxy/connection/client/InitialLoginSessionHandler.java

@@ -68,12 +68,14 @@ public class InitialLoginSessionHandler implements MinecraftSessionHandler {
   private @MonotonicNonNull ServerLogin login;
   private byte[] verify = EMPTY_BYTE_ARRAY;
   private LoginState currentState = LoginState.LOGIN_PACKET_EXPECTED;
+  private boolean forceKeyAuthentication;
 
   InitialLoginSessionHandler(VelocityServer server, MinecraftConnection mcConnection,
                              LoginInboundConnection inbound) {
     this.server = Preconditions.checkNotNull(server, "server");
     this.mcConnection = Preconditions.checkNotNull(mcConnection, "mcConnection");
     this.inbound = Preconditions.checkNotNull(inbound, "inbound");
+    this.forceKeyAuthentication = Boolean.getBoolean("auth.forceSecureProfiles");
   }
 
   @Override
@@ -92,7 +94,7 @@ public class InitialLoginSessionHandler implements MinecraftSessionHandler {
         return true;
       }
     } else if (mcConnection.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0
-            && server.getConfiguration().isForceKeyAuthentication()) {
+            && forceKeyAuthentication) {
       inbound.disconnect(Component.translatable("multiplayer.disconnect.missing_public_key"));
       return true;
     }