Eliminate the use of xtend in compatibility/inventory-topology-compatibility

opendaylight/md-sal/compatibility/inventory-topology-compatibility/src/main/java/org/opendaylight/controller/md/compatibility/topology/TopologyMapping.xtend
opendaylight/md-sal/compatibility/inventory-topology-compatibility/src/main/java/org/opendaylight/controller/md/compatibility/topology/TopologyReader.xtend
opendaylight/md-sal/compatibility/inventory-topology-compatibility/src/main/java/org/opendaylight/controller/md/compatibility/switchmanager/CompatibleSwitchManager.xtend
opendaylight/md-sal/compatibility/inventory-topology-compatibility/src/main/java/org/opendaylight/controller/md/compatibility/switchmanager/ConfigurableSwitchManager.xtend
opendaylight/md-sal/compatibility/inventory-topology-compatibility/src/main/java/org/opendaylight/controller/md/compatibility/inventory/InventoryReader.xtend
opendaylight/md-sal/compatibility/inventory-topology-compatibility/src/main/java/org/opendaylight/controller/md/compatibility/topologymanager/CompatibleTopologyManager.xtend
opendaylight/md-sal/compatibility/inventory-topology-compatibility/src/main/java/org/opendaylight/controller/md/compatibility/topologymanager/ConfigurableLinkManager.xtend
opendaylight/md-sal/compatibility/inventory-topology-compatibility/src/main/java/org/opendaylight/controller/md/compatibility/topologymanager/AdSalTopologyMapping.xtend

should all be convertible to java.