Don't enable fly mode on login when player is in water (#6490)

Fixes #6198

Author: JRoy

Essentials/src/main/java/com/earth2me/essentials/EssentialsPlayerListener.java

@@ -513,7 +513,8 @@ private void joinFlow(final User user, final long currentTime, final String mess
 
         if (user.isAuthorized("essentials.fly.safelogin")) {
             user.getBase().setFallDistance(0);
-            if (LocationUtil.shouldFly(ess, user.getLocation())) {
+            final boolean inWater = VersionUtil.getServerBukkitVersion().isHigherThanOrEqualTo(VersionUtil.v1_17_R01) && user.getBase().isInWater();
+            if (!inWater && LocationUtil.shouldFly(ess, user.getLocation())) {
                 user.getBase().setAllowFlight(true);
                 user.getBase().setFlying(true);
                 if (!restoreFly && ess.getSettings().isSendFlyEnableOnJoin()) {