getHeaderLines() returns incomplete lines
`$request->getHeaderLines()` creates an array from `$request->getRawHeaders()`
It explodes lines on **"\:"** and returns the first value as the key and the second value as the header value. This shortens header values with **"\:"** in their value. 
For example, the user agent:
`Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:61.0) Gecko/20100101 Firefox/61.0`
is returned
`[User-Agent] => Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv
`in $request->getHeaderLines() 