NPE reported in RibImpl class during controller shutdown when debugs enabled

opendaylight-user@root>
SLF4J: Failed toString() invocation on an object of type [org.opendaylight.protocol.bgp.rib.impl.config.RibImpl]
java.lang.NullPointerException
at org.opendaylight.protocol.bgp.rib.impl.config.RibImpl.toString(RibImpl.java:217)
at org.slf4j.helpers.MessageFormatter.safeObjectAppend(MessageFormatter.java:297)
at org.slf4j.helpers.MessageFormatter.deeplyAppendParameter(MessageFormatter.java:269)
at org.slf4j.helpers.MessageFormatter.arrayFormat(MessageFormatter.java:227)
at org.slf4j.helpers.MessageFormatter.format(MessageFormatter.java:124)
at org.ops4j.pax.logging.slf4j.Slf4jLogger.debug(Slf4jLogger.java:292)
at org.opendaylight.protocol.bgp.rib.impl.config.BgpDeployerImpl.onGlobalRemoved(BgpDeployerImpl.java:203)
at Proxy851564cd_7b30_43f0_b1bb_2659e569b90f.onGlobalRemoved(Unknown Source)
at org.opendaylight.controller.config.yang.bgp.rib.impl.RIBImplModule$1.handleInvocation(RIBImplModule.java:100)
at com.google.common.reflect.AbstractInvocationHandler.invoke(AbstractInvocationHandler.java:87)
at org.opendaylight.controller.config.yang.bgp.rib.impl.$Proxy156.close(Unknown Source)
at org.opendaylight.controller.config.manager.impl.dependencyresolver.DestroyedModule.close(DestroyedModule.java:52)
at org.opendaylight.controller.config.manager.impl.ConfigRegistryImpl.close(ConfigRegistryImpl.java:515)
at org.opendaylight.controller.config.manager.impl.osgi.ConfigManagerActivator.closeAllConfigModules(ConfigManagerActivator.java:168)
at org.opendaylight.controller.blueprint.BlueprintBundleTracker.shutdownAllContainers(BlueprintBundleTracker.java:238)
at org.opendaylight.controller.blueprint.BlueprintBundleTracker.bundleChanged(BlueprintBundleTracker.java:150)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.dispatchEvent(BundleContextImpl.java:847)
at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148)
at org.eclipse.osgi.framework.internal.core.Framework.publishBundleEventPrivileged(Framework.java:1568)
at org.eclipse.osgi.framework.internal.core.Framework.publishBundleEvent(Framework.java:1504)
at org.eclipse.osgi.framework.internal.core.Framework.publishBundleEvent(Framework.java:1499)
at org.eclipse.osgi.framework.internal.core.Framework.shutdown(Framework.java:681)
at org.eclipse.osgi.framework.internal.core.Framework.close(Framework.java:600)
at org.eclipse.osgi.framework.internal.core.InternalSystemBundle$1.run(InternalSystemBundle.java:261)
at java.lang.Thread.run(Thread.java:745)