* check if a plugin has an executor service

* checkstyle

In this little patch I replaced an i which caused my build process to crash with an i

…rMC#591)

We don't need to track this information since Velocity uses the JoinGame packet, which is about as good of a server rejoin mechanism we're likely to get in vanilla Minecraft.

Update with upstream

Co-authored-by: RednedEpic <redned235@gmail.com>
Co-authored-by: Gero <gecam59@gmail.com>

I don't see where this was ever done, and don't see how plugin messaging
could of ever worked, at least within the confines of CB and co, given
the fact that we never seemed to be sending this to the backend?

* Send LoginAcknowledged immediately

* Resend player list header/footer after backend server switched to config state

* Fix clearHeaderAndFooter not clearing fields in ConnectedPlayer

* Clear boss bars, header/footer, tab list when switching client to config state

* Send client settings in config state

* fix: commands flagged as signed without signed arguments

* feat: improve error message for illegal protocol state.

…rMC#1100)

…isting in the phase (PaperMC#1107)

# Conflicts:
#	proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/keyed/KeyedCommandHandler.java
#	proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/session/SessionCommandHandler.java