Make sure log_handlers parameter contains only supported handler names.
Empty handlers list is now rejected because we expect at least one
logger may be enabled in real deployments.
Also validate log_level and log_facility.
Change-Id: I35e2f1f232bd6b5723f61442a3e4a4ba3315547f
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>
7bdc9ead83