Columns::getProvidersColumns

protected function getProvidersColumns(): array
{
	if (!isset($this->providersColumns))
	{
		$this->providersColumns = [];

		foreach ($this->providers as $provider)
		{
			$providerColumns = $provider->prepareColumns();
			if (empty($providerColumns))
			{
				continue;
			}

			$providerClass = get_class($provider);
			$this->providersColumns[$providerClass] = $providerColumns;
		}
	}

	return $this->providersColumns;
}