Modify Jetty code so it compiles with 1.8 type rules

Contains a code change from:
https://github.com/eclipse/jetty.project/commit/d89aa3a86615c64edb4bfb861b790d3f818716c5

The change to Request.java is bespoke.

Bug: 26753820
(cherry-picked from 806b0b93225bdf4a36d560351642126100e1950e)

Change-Id: I5894b3ca0e5fb8af161f0d1880d97d86a6f67070
2 files changed