Minor Optimisations

[stuartwdouglas]

These provide some minor performance improvements to reduce object allocation. In particular:

• Don't allocate a list on a getAll call if there are no headers
• Don't create a StringBuilder if not required, as most paths don't contain a '.' character

[vietj]

there are actually failing tests in the CI

Failed tests: 
12482  HttpUtilsTest.testMultipleSlashPath1:119 expected:</[]blah> but was:</[/]blah>
12483  HttpUtilsTest.testMultipleSlashPath2:124 expected:</[]blah> but was:</[//]blah>
12484  HttpUtilsTest.testMultipleSlashPath3:129 expected:</foo/[]blah> but was:</foo/[/]blah>
12485  HttpUtilsTest.testMultipleSlashPath4:134 expected:</foo/[blah]/> but was:</foo/[/blah//]/>
12486  HttpUtilsTest.testMultipleTrailingSlashes1:164 expected:</blah/[]> but was:</blah/[/]>
12487  HttpUtilsTest.testMultipleTrailingSlashes2:169 expected:</blah/[]> but was:</blah/[//]>

[stuartwdouglas]

Fixed

[Sanne]

up :)