Fixed a bug where sorting on displayProperty was case sensitive

Author: pkempenaers

src/app/component/dropdownTree.controller.js

@@ -77,6 +77,16 @@
 if (!vm.settings.sortByDisplayProperty) {
 return 0;
 }
+if (a.type === 'string') {
+const aLowerCase = a.value.toLowerCase();
+const bLowerCase = b.value.toLowerCase();
+if (aLowerCase < bLowerCase) {
+return -1;
+} else if (aLowerCase > bLowerCase) {
+return 1;
+}
+return 0;
+}
 if (a.value < b.value) {
 return -1;
 } else if (a.value > b.value) {