The plugin doesn't work on Velocity.

[04:29:25 ERROR]: Unable to load plugin plugins/ECRelay-1.1.jar
com.velocitypowered.api.plugin.InvalidPluginException: The plugin file ECRelay-1.1.jar appears to be a Bukkit or BungeeCord plugin. Velocity does not support Bukkit or BungeeCord plugins.
at com.velocitypowered.proxy.plugin.loader.java.JavaPluginLoader.getSerializedPluginInfo(JavaPluginLoader.java:164) ~[server.jar:3.3.0-SNAPSHOT (git-75d6dcc1-b371)]
at com.velocitypowered.proxy.plugin.loader.java.JavaPluginLoader.loadCandidate(JavaPluginLoader.java:64) ~[server.jar:3.3.0-SNAPSHOT (git-75d6dcc1-b371)]
at com.velocitypowered.proxy.plugin.VelocityPluginManager.loadPlugins(VelocityPluginManager.java:96) ~[server.jar:3.3.0-SNAPSHOT (git-75d6dcc1-b371)]
at com.velocitypowered.proxy.VelocityServer.loadPlugins(VelocityServer.java:364) ~[server.jar:3.3.0-SNAPSHOT (git-75d6dcc1-b371)]
at com.velocitypowered.proxy.VelocityServer.start(VelocityServer.java:241) ~[server.jar:3.3.0-SNAPSHOT (git-75d6dcc1-b371)]
at com.velocitypowered.proxy.Velocity.main(Velocity.java:70) ~[server.jar:3.3.0-SNAPSHOT (git-75d6dcc1-b371)]