function addToChangeSet(oChange) {
			if (!mergePatch(oChange)) {
				if (oChange.method === "DELETE" && oChange.headers["If-Match"]
						&& oChange.headers["If-Match"]["@odata.etag"]
						&& aChangeSet.find(function (oCandidate) {
							return oCandidate.headers["If-Match"] === oChange.headers["If-Match"];
						})) {
					oChange.headers["If-Match"] = {"@odata.etag" : "*"};
				}
				aChangeSet.push(oChange);
			}
		}
Cleans up the change sets contained in the given requests by merging PATCHes, deleting
empty change sets and unwrapping change sets containing only one request in case change sets
are optional.

@param {object[]} aRequests The requests
@returns {boolean} Whether there is a modifying request in aRequests

@private
@see sap.ui.model.odata.v4.lib._Requestor#isChangeSetOptional