addButton(new Button(relX + 18, relY + 15, 5, 20, "PURGE", button -> sent the message to the server));
is that so hard ?
https://github.com/drmdgg/marijuanacraft1.14.4/blob/master/src/main/java/drmdgg/marijuanacraft/network/PacketHandler.java#L49
you want to not this
https://github.com/drmdgg/marijuanacraft1.14.4/blob/master/src/main/java/drmdgg/marijuanacraft/network/Networking.java#L12
is a bad name
give the constructor only the blockPos
in the encode method encode the blockPos look inside the PacketBuffer to see how
in decode return a new packet