function updateItemUsage(self, oItem) {
			if (self._metadata.__byKey__[oItem.oData.key] != null) { // ItemData already exists, we need to remove the old position index
				var oldIndex = self._metadata.__byKey__[oItem.oData.key];
				delete self._metadata.__byIndex__[oldIndex];
				Log.debug("Cache Manager LRUPersistentCache: set/internalset - item already exists, so its indexes are updated");
			}
			self._metadata.__byIndex__[oItem.oData.lu] = oItem.oData.key;
			self._metadata.__byKey__[oItem.oData.key] = oItem.oData.lu;

			seekMetadataLRU(self);
		}
Set/updates item's usage by setting LRU indexes and moves the LRU pointer if needed.
@param {sap.ui.core.cache.LRUPersistenceCache} self the <code>this</code> instance
@param {Item} oItem the item to update indexes for