RFR: 1542: Census Namespace missing hashCode and equals [v2]

[Erik Joelsson]

> 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.

Erik Joelsson has updated the pull request incrementally with one additional commit since the last revision:

  Use Object.equals

-------------

Changes:
  - all: https://git.openjdk.org/skara/pull/1356/files
  - new: https://git.openjdk.org/skara/pull/1356/files/e0f5d6ea..afcdb1f8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1356&range=01
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1356&range=00-01

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 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