RFR: 8268900: com/sun/net/httpserver/Headers.java: Fix indentation and whitespace

[Julia Boes]

This cleanup-only change fixes the indentation of all members from 8 to 4 spaces and removes whitespace in method invocations (example: `foo ()` -> `foo()`). It also removes superfluous type parameters on lines 83, 168, 206.

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Commit messages:
 - initial change

Changes: https://git.openjdk.java.net/jdk/pull/4517/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4517&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268900
  Stats: 163 lines in 1 file changed: 32 ins; 33 del; 98 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4517.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4517/head:pull/4517

PR: https://git.openjdk.java.net/jdk/pull/4517