This flag contains the same message as eula.txt (albeit with proper grammar for 3rd person plural). By setting this flag you are agreeing to the terms listed in the message printed upon setting this flag, which are no different from those agreed to by any other method.
This feature only exists for hosting companies and people who manage servers in bulk who wish to agree to the terms by setting a flag in a script.
+ System.err.println( "You have used the Spigot command line EULA agreement flag." );
+ System.err.println( "By using this setting you are indicating your agreement to Mojang's EULA (https://account.mojang.com/documents/minecraft_eula)." );
+ System.err.println( "If you do not agree to the above EULA please stop your server and remove this flag immediately." );