RFR: JDK-8274233: Minor cleanup for ToolBox

[Jonathan Gibbons]

Please review some superficial cleanup to the ToolBox class.  There are no API changes and no changes to any tests.

1. Change `Paths.get` to `Path.of`
2. Minor code cleanup suggested by IDE, such as removing unnecessary type parameters, etc
3. Reformat doc comments to commonly prevailing standards

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Commit messages:
 - JDK-8274233: Minor cleanup for ToolBox

Changes: https://git.openjdk.java.net/jdk/pull/5667/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5667&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274233
  Stats: 111 lines in 1 file changed: 47 ins; 12 del; 52 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5667.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5667/head:pull/5667

PR: https://git.openjdk.java.net/jdk/pull/5667