Item::getAllImplementations

private function getAllImplementations(): array
{
	if (isset($this->allImplementationsCache) && is_array($this->allImplementationsCache))
	{
		return $this->allImplementationsCache;
	}

	$implementations = [];
	foreach ($this->fieldToImplementationMap as $implementation)
	{
		if (!in_array($implementation, $implementations, true))
		{
			$implementations[] = $implementation;
		}
	}

	$this->allImplementationsCache = $implementations;

	return $implementations;
}