ACCUMULO-2524 Check for null args to ProblemReport constructors
Merge branch '1.4.5-SNAPSHOT' into 1.5.2-SNAPSHOT
Merge branch '1.5.2-SNAPSHOT' into 1.6.0-SNAPSHOT
Merge branch '1.6.0-SNAPSHOT'
ACCUMULO-2524 Update ProblemReport to use Preconditions over ArgumentChecker