Merge pull request #1945 from jbertram/2.3.x

HORNETQ-1374 Wildcard test
2.3.23.Final release
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Merge pull request #1946 from clebertsuconic/2.3.x

release 2.3.23
BZ-1160683 NoSuchMethodError during init

When compiled by JDK 8 targeting Java 6 and then run on JDK 6 or 7 the
ConcurrentHashMap#keyset() method can fail because the return types
changed in Java 8. Using ConcurrentMap interface to resolve the issue.