code: @Override
  	public IdentifyingToken validate(IdentifyingToken token, @Nullable ChargingStationId chargingStationId) {
  		for (AuthorizationProvider provider : providers) {
  			IdentifyingToken validatedToken = provider.validate(token, chargingStationId);
  			if (validatedToken.isValid()) {
  				return validatedToken;
  			}
  		}
  		return token;
  	}
docs: Validates the token with the configured authentication providers, as soon
  as one provider provides valid authorization this will be the result.
  
  @param token identifying token for which authorization is required
  @param chargingStationId optional charging station id for this authorization
  @return validated IdentifyingToken