Most ftp-clients sends FEAT before authentication

Most clients sends FEAT command before authentication. So, it should be listed in NON_AUTHENTICATED_COMMANDS in org.apache.ftpserver.impl.DefaultFtpHandler. Please, find the patch below.

— a/core/src/main/java/org/apache/ftpserver/impl/DefaultFtpHandler.java
+++ b/core/src/main/java/org/apache/ftpserver/impl/DefaultFtpHandler.java
@@ -48,7 +48,7 @@ public class DefaultFtpHandler implements FtpHandler {
private final Logger LOG = LoggerFactory.getLogger(DefaultFtpHandler.class);

private final static String[] NON_AUTHENTICATED_COMMANDS = new String[]

{ - "USER", "PASS", "AUTH", "QUIT", "PROT", "PBSZ" }

;
+ "USER", "PASS", "AUTH", "QUIT", "PROT", "PBSZ", "FEAT" };

private FtpServerContext context;