Updated usage of deprecated FormatUtils.getTimeDuration to FormatUtils.getPreciseTimeDuration
Implemented prioritized handling of appending the default realm
A realm-qualified principal will not be modified before authentication
A principal shortname will have Default Realm appended to it when it is not blank before authentication
A principal shortname will not be modified if Default Realm is blank, and the underlying kerberos implementation will append the default_realm configured in krb5.conf
In nifi-security-util
added KerberosPrincipalParser for determining the realm of a kerberos principal
added tests for KerberosPrincipalParser
updated pom with spock-core as a test dependency
This closes#3446.
Signed-off-by: Kevin Doran <kdoran@apache.org>