RFR: 1542: Census Namespace missing hashCode and equals

Thu Aug 11 20:45:37 UTC 2022

The Namespace class is missing hashCode and equals. This patch adds implementations for those two methods. The other data classes in the Census module already have them. 

This is preventing the change in [SKARA-1529](https://bugs.openjdk.org/browse/SKARA-1529) from actually taking effect, as we can't compare two instances of Namespace to see if they have the same contents.

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Commit messages:
 - SKARA-1542

Changes: https://git.openjdk.org/skara/pull/1356/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1356&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-1542
  Stats: 17 lines in 1 file changed: 17 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/skara/pull/1356.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1356/head:pull/1356

PR: https://git.openjdk.org/skara/pull/1356