[master] Tomek's changes + init + deinit fixes

src/bin/dhcp4/json_config_parser.cc

@@ -24,6 +24,7 @@
 #include <dhcpsrv/parsers/option_data_parser.h>
 #include <dhcpsrv/parsers/simple_parser4.h>
 #include <dhcpsrv/parsers/shared_networks_list_parser.h>
+#include <dhcpsrv/host_data_source_factory.h>
 #include <dhcpsrv/timer_mgr.h>
 #include <hooks/hooks_parser.h>
 #include <config/command_mgr.h>
@@ -297,6 +298,9 @@ configureDhcp4Server(Dhcpv4Srv&, isc::data::ConstElementPtr config_set,
     // for option definitions. This is equivalent to committing empty container.
     LibDHCP::setRuntimeOptionDefs(OptionDefSpaceContainer());
 
+    // Print the list of known backends.
+    HostDataSourceFactory::printRegistered();
+
     // Answer will hold the result.
     ConstElementPtr answer;
     // Rollback informs whether error occurred and original data