fix(property-form): set the cache after the ontology changes with the…

… new lastModificationDate to prevent 409 http errors (#824)

src/app/project/ontology/property-form/property-form.component.ts

@@ -503,6 +503,9 @@ export class PropertyFormComponent implements OnInit {
                                 }
                             );
                         }
+
+                        this.ontology.lastModificationDate = this.lastModificationDate;
+                        this._cache.set('currentOntology', this.ontology);
                     },
                     (error: ApiResponseError) => {
                         this.error = true;