src/Container/Container.php
public function has($className, array $parameters = [])
    {
        if ($this->injectSelf($className)) {
            return true;
        }

        $parameterKey = $this->getParameterStoreKey($parameters);

        $className = $this->resolve($className);

        return isset($this->services[$className][$parameterKey]);
    }
public function has($className, array $parameters = [])
    {
        if ($this->injectSelf($className)) {
            return true;
        }

        $parameterKey = $this->getParameterStoreKey($parameters);

        $className = $this->resolve($className);

        return isset($this->services[$className][$parameterKey]);
    }
Check if there is an instance in the container

@param string $className
@param array $parameters
@return bool