Fix return type of FileGenerator::getClass

[janvernieuwe]

Provide a narrative description of what you are trying to accomplish:

• [Y ] Is this related to quality assurance?
  Return type of \Zend\Code\Generator\FileGenerator::getClass only has ClassGenerator while it can also return false when the classes array is empty.
  PHPStan will whine about this, because it should always return a true-thy return, also it gives the perception it will always return the ClassGenerator (while it doesn't always do that)

Therefor I added the false to the return type in the docblock.

[weierophinney]

This repository has been closed and moved to laminas/laminas-code; a new issue has been opened at laminas/laminas-code#2.

[weierophinney]

This repository has been moved to laminas/laminas-code. If you feel that this patch is still relevant, please re-open against that repository, and reference this issue. To re-open, we suggest the following workflow:

• Squash all commits in your branch (git rebase -i origin/{branch})
• Make a note of all changed files (`git diff --name-only origin/{branch}...HEAD
• Run the laminas/laminas-migration tool on the code.
• Clone laminas/laminas-code to another directory.
• Copy the files from the second bullet point to the clone of laminas/laminas-code.
• In your clone of laminas/laminas-code, commit the files, push to your fork, and open the new PR.
  We will be providing tooling via laminas/laminas-migration soon to help automate the process.