system/HTTP/IncomingRequest.php
public function getFile(string $fileID)
	{
		if (is_null($this->files))
		{
			$this->files = new FileCollection();
		}

		return $this->files->getFile($fileID);
	}
public function getFile(string $fileID)
	{
		if (is_null($this->files))
		{
			$this->files = new FileCollection();
		}

		return $this->files->getFile($fileID);
	}
Retrieves a single file by the name of the input field used
to upload it.

@param string $fileID

@return UploadedFile|null