UnionTypeCodec should not throw raw Exception

This is a callable, and we know what types of exceptions can be thrown,
so get rid of the implied sonar warning.

Change-Id: Iab62d6749cd1d33096297c2072e02c42ddebd878
Signed-off-by: Robert Varga <rovarga@cisco.com>
Remove unused arguments from UnionTypeCodec.loader()

The two codecs passed in were unused, so remove them, fix the callsite
and remove the useless warnings suppression.

Change-Id: Ib3d052109303c1c18f9a4d58d2eafeefea37caba
Signed-off-by: Robert Varga <rovarga@cisco.com>