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
Change-Id: Iacf7b94054595370435b2a31b3d62e195a8c7e25
2 files changed