src/Container.php
public function getMutableFiles(Finder $finder)
    {
        if (empty($this->mutables)) {
            $generator = $this->getGenerator();
            $generator->generate($finder);
            $this->mutables = $generator->getMutables();
        }
        return $this->mutables;
    }
public function getMutableFiles(Finder $finder)
    {
        if (empty($this->mutables)) {
            $generator = $this->getGenerator();
            $generator->generate($finder);
            $this->mutables = $generator->getMutables();
        }
        return $this->mutables;
    }
Generate Mutants!

@return array