public function getStatistics()
    {
        return [
            'currentCallCount'       => count($this->calls),
            'registeredAt'           => $this->registeredAt,
            'invocationCount'        => $this->invocationCount,
            'invocationAverageTime'  => $this->invocationAverageTime,
            'busyTime'               => $this->busyTime,
            'busyStart'              => $this->busyStart,
            'lastIdledAt'            => $this->lastIdledAt,
            'lastCallStartedAt'      => $this->lastCallStartedAt,
            'completedCallTimeTotal' => $this->completedCallTimeTotal
        ];
    }