Merge branch '9.1.x' into skrastev/fix-7469-9.1.x

Author: dkamburov

projects/igniteui-angular/src/lib/grids/grid/grid-api.service.ts

@@ -43,12 +43,16 @@ export class IgxGridAPIService extends GridBaseAPIService<IgxGridComponent> {
             names.forEach((colName) => {
                 const grExprIndex = groupingState.findIndex((exp) => exp.fieldName === colName);
                 const grpExpandState = this.grid.groupingExpansionState;
-                /* remove expansion states related to the cleared group
-                and all with deeper hierarchy than the cleared group */
-                this.grid.groupingExpansionState = grpExpandState
-                    .filter((val) => {
-                        return val.hierarchy && val.hierarchy.length <= grExprIndex;
-                    });
+                 /* remove expansion states related to the cleared group
+                    and all with deeper hierarchy than the cleared group */
+                const newExpandState = grpExpandState.filter((val) => {
+                    return val.hierarchy && val.hierarchy.length <= grExprIndex;
+                });
+                /* Do not set the new instance produced by filter
+                    when there are no differences between expansion states */
+                if (newExpandState.length !== grpExpandState.length) {
+                   this.grid.groupingExpansionState = newExpandState;
+                }
             });
         } else {
             // clear all

projects/igniteui-angular/src/lib/grids/grid/grid-summary.spec.ts

@@ -1684,6 +1684,7 @@ describe('IgxGrid - Summaries #grid', () => {
             GridSummaryFunctions.verifyColumnSummaries(summaryRow, 4, ['Count', 'Min', 'Max', 'Sum', 'Avg'], ['2', '31', '43', '74', '37']);
 
             grid.clearGrouping('OnPTO');
+            fix.detectChanges();
             verifyBaseSummaries(fix);
             verifySummariesForParentID17(fix, 3);
             verifySummariesForParentID19(fix, 6);