tmf: Remove an annotation temporarily to work around Sonarqube bug

tmf: Remove an annotation temporarily to work around Sonarqube bug

There is a Sonarqube bug with type annotations and arrays, see
https://groups.google.com/forum/#!topic/sonarqube/VTsAYxhGRiA
and
https://github.com/SonarSource/sonar-java/pull/537

By removing the @NonNull, it brings back a warning but makes the
Sonarqube build work again.

Change-Id: I6a03295432c7c452b4dca9018d4c17ba4b991980
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/62684
Reviewed-by: Hudson CI
Reviewed-by: Francis Giraldeau <francis.giraldeau@gmail.com>