code: function preloadDesigntimeLibrary(oMetadata) {
  		//preload the designtime data for the library
  		var sLibrary = oMetadata.getLibraryName(),
  			sPreload = sap.ui.getCore().getConfiguration().getPreload(),
  			oLibrary = sap.ui.getCore().getLoadedLibraries()[sLibrary];
  		if (oLibrary && oLibrary.designtime) {
  			var oPromise;
  			if (sPreload === "async" || sPreload === "sync") {
  				//ignore errors _loadJSResourceAsync is true here, do not break if there is no preload.
  				oPromise = sap.ui.loader._.loadJSResourceAsync(oLibrary.designtime.replace(/\.designtime$/, "-preload.designtime.js"), true);
  			} else {
  				oPromise = Promise.resolve();
  			}
  			return new Promise(function(fnResolve) {
  				oPromise.then(function() {
  					sap.ui.require([oLibrary.designtime], function(oLib) {
  						fnResolve(oLib);
  					});
  				});
  			});
  		}
  		return Promise.resolve(null);
  	}
docs: ---- Design Time capabilities ------------------------------------------------------------- 
  Returns a promise that resolves if the designtime preload of a library is loaded for the given oMetadata
  object is loaded.
  If the corresponding library does not contain a designtime setting with a module path to the library.designtime file
  the promise resolves immediately.
  
  @private