Defining friendly_name for a switch created in custom component

https://github.com/peterbuga/HASS-sonoff-ewelink/blob/master/sonoff.py

Trying to create an attribute friendly_name to represent self._device_name

class SonoffDevice(Entity):
"""Representation of a Sonoff device"""

def __init__(self, hass, device):
    """Initialize the device."""

    self._hass          = hass
    self._name          = 'sonoff_{}'.format(device['deviceid']) 
    self._device_name   = device['name']
    self._deviceid      = device['deviceid']
    self._user_apikey   = device['apikey']
    self._state         = device['params']['switch'] == 'on'
    self._available     = device['online']

    self._attributes    = {
        'device_name'   : self._device_name,
        'device_id'     : self._deviceid,
        'friendly_name' : self._device_name
    }

def get_device(self, deviceid):
    for device in self._hass.data[DOMAIN].get_devices():
        if 'deviceid' in device and device['deviceid'] == deviceid:
            return device

    return None

def get_state(self, deviceid):
    device = self.get_device(deviceid)
    return device['params']['switch'] == 'on' if device else False

def get_available(self, deviceid):
    device = self.get_device(deviceid)
    return device['online'] if device else False

@property
def should_poll(self):
    """Return the polling state."""
    return True

@property
def name(self):
    """Return the name of the switch."""
    return self._name

@property
def is_on(self):
    """Return true if device is on."""
    return self.get_state(self._deviceid)

@property
def available(self):
    """Return true if device is online."""
    return self.get_available(self._deviceid)

# @Throttle(MIN_TIME_BETWEEN_UPDATES)
def update(self):
    """Update device state."""

    # we don't update here because there's 1 single thread that can be active at anytime
    # i.e. eWeLink API allows only 1 active session
    pass

def turn_on(self, **kwargs):
    """Turn the device on."""
    self._state = self._hass.data[DOMAIN].switch(self._deviceid, True)
    self.schedule_update_ha_state()

def turn_off(self, **kwargs):
    """Turn the device off."""
    self._state = self._hass.data[DOMAIN].switch(self._deviceid, False)
    self.schedule_update_ha_state()

@property
def device_state_attributes(self):
    """Return device specific state attributes."""
    return self._attributes

Nothing seems to be working
Would really appreciate your help.