code: func (c *Callbacks) OnCDOTAUserMsg_CustomHeaderMessage(fn func(*dota.CDOTAUserMsg_CustomHeaderMessage) error) {
  	c.onCDOTAUserMsg_CustomHeaderMessage = append(c.onCDOTAUserMsg_CustomHeaderMessage, fn)
  }
docs: // OnCDOTAUserMsg_CustomHeaderMessage registers a callback for EDotaUserMessages_DOTA_UM_CustomHeaderMessage