Custom mavros message to enable communication between Gazebo and PX4

Hi, I am trying to add a custom mavros message. Therefore I have already add a new plugin called gazebo_pos.cpp


Plugin to transport data from Gazebo via MAVLink to PX4 without coordinate transformation


#include <mavros/mavros_plugin.h>
#include <pluginlib/class_list_macros.h>

#include <geometry_msgs/PoseStamped.h>      // this is the message type which will be used

namespace mavros {
namespace extra_plugins{
 * brief Gazebo to PX4 plugin
class GazeboPosPlugin : public plugin::PluginBase
 GazeboPosPlugin() : PluginBase(),
{ }

void initialize(UAS &uas_)

	gazebo_pos_sub = mp_nh.subscribe("pose", 1, &GazeboPosPlugin::gazebo_pos_cb, this);


Subscriptions get_subscriptions()
	return { /* Rx disabled */ };

ros::NodeHandle mp_nh;

ros::Subscriber gazebo_pos_sub;

// callback function
void gazebo_pos_cb(const geometry_msgs::PoseStamped::ConstPtr &pose)
    mavlink::common::msg::GAZEBO_POS pos;

	pos.qw = pose->pose.orientation.w;
	pos.qx = pose->pose.orientation.x;
	pos.qy = pose->pose.orientation.y;
	pos.qz = pose->pose.orientation.z;

	pos.x = pose->pose.position.x;
	pos.y = pose->pose.position.y;
	pos.z = pose->pose.position.z;

}	// namespace extra_plugins
}	// namespace mavros

PLUGINLIB_EXPORT_CLASS(mavros::extra_plugins::GazeboPosPlugin, mavros::plugin::PluginBase)

The problem is when I try to compile the code I get the error message:

error: ‘GAZEBO_POS’ is not a member of ‘mavlink::common::msg’
     mavlink::common::msg::GAZEBO_POS pos;

I already added into my MAVLink repo the necessary message. The question is how can I make the message visible for mavros?