Fix ITDevJSFHotReloadTest.testStudioTab failure on MongoDB

Caused by: java.lang.NullPointerException
	at org.nuxeo.ecm.core.mongodb.kv.MongoDBKeyValueStore.compareAndSet(MongoDBKeyValueStore.java:406) ~[nuxeo-core-mongodb-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.core.mongodb.kv.MongoDBKeyValueStore.compareAndSet(MongoDBKeyValueStore.java:383) ~[nuxeo-core-mongodb-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.runtime.kv.AbstractKeyValueStoreProvider.compareAndSet(AbstractKeyValueStoreProvider.java:188) ~[nuxeo-runtime-kv-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.core.api.LockHelper.tryLock(LockHelper.java:100) ~[nuxeo-core-api-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.core.api.LockHelper.doAtomically(LockHelper.java:73) ~[nuxeo-core-api-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.core.api.AbstractSession.getOrCreateDocument(AbstractSession.java:2552) ~[nuxeo-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.platform.userworkspace.core.service.AbstractUserWorkspaceImpl.lambda$getExistingUserWorkspace$5(AbstractUserWorkspaceImpl.java:290) ~[nuxeo-platform-userworkspace-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.core.api.CoreInstance$2.run(CoreInstance.java:206) ~[nuxeo-core-api-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.core.api.UnrestrictedSessionRunner.runUnrestricted(UnrestrictedSessionRunner.java:131) ~[nuxeo-core-api-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.core.api.CoreInstance.doPrivileged(CoreInstance.java:208) ~[nuxeo-core-api-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.platform.userworkspace.core.service.AbstractUserWorkspaceImpl.getExistingUserWorkspace(AbstractUserWorkspaceImpl.java:288) ~[nuxeo-platform-userworkspace-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.platform.userworkspace.core.service.AbstractUserWorkspaceImpl.getCurrentUserPersonalWorkspace(AbstractUserWorkspaceImpl.java:243) ~[nuxeo-platform-userworkspace-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.platform.userworkspace.core.service.AbstractUserWorkspaceImpl.getCurrentUserPersonalWorkspace(AbstractUserWorkspaceImpl.java:213) ~[nuxeo-platform-userworkspace-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.platform.userworkspace.core.service.AbstractUserWorkspaceImpl.getUserFavorites(AbstractUserWorkspaceImpl.java:470) ~[nuxeo-platform-userworkspace-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.collections.core.FavoritesManagerImpl.getFavorites(FavoritesManagerImpl.java:54) ~[nuxeo-platform-collections-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.collections.core.FavoritesManagerImpl.getFavorites(FavoritesManagerImpl.java:49) ~[nuxeo-platform-collections-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.collections.core.FavoritesManagerImpl.isFavorite(FavoritesManagerImpl.java:60) ~[nuxeo-platform-collections-core-11.1-SNAPSHOT.jar:?]
	at org.nuxeo.ecm.webapp.collections.FavoritesActionBean.canCurrentDocumentBeRemovedFromFavorites(FavoritesActionBean.java:86) ~[nuxeo-platform-webapp-base-11.1-SNAPSHOT.jar:?]