Minor improvements to sample instance files

instance/start.bat

@@ -1,4 +1,4 @@
 :;cd "$(dirname "$0")"; exec ./tmux.sh
 @echo off
 cd /D "%~dp0"
-java -Xmx1024M -Xms1024M -jar server.jar nogui
+java -Dlog4j2.formatMsgNoLookups=true -Xmx1024M -Xms1024M -jar server.jar nogui

instance/start.sh

@@ -6,5 +6,7 @@ if ! [[ -e ./vars ]] ; then
 fi
 source ./vars
 
+JAVA="${JAVA:-java}"
+
 command "$JAVA" $JAVA_PARAMS -jar "$SERVER" nogui
 sleep 10

instance/vars.example

@@ -1,3 +1,8 @@
+#!/bin/bash
 JAVA_PARAMS="-Dlog4j2.formatMsgNoLookups=true -Xmx1024M -Xms1024M"
 JAVA=java
 SERVER=server.jar
+# Overriding $PATH can be useful to force third party launch scripts to use the
+# correct Java, and is just a more elegant way than the above method.
+# For example:
+# PATH="/usr/lib/jvm/java-17-openjdk/bin:$PATH" ; export PATH