Avoid concurrent modification errors by copying list of filters.

Fixes gh-1073

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/route/RouteDefinitionRouteLocator.java

@@ -226,14 +226,15 @@ public class RouteDefinitionRouteLocator
 		// TODO: support option to apply defaults after route specific filters?
 		if (!this.gatewayProperties.getDefaultFilters().isEmpty()) {
 			filters.addAll(loadGatewayFilters(DEFAULT_FILTERS,
-					this.gatewayProperties.getDefaultFilters()));
+					new ArrayList<>(this.gatewayProperties.getDefaultFilters())));
 		}
 
 		if (!routeDefinition.getFilters().isEmpty()) {
 			filters.addAll(loadGatewayFilters(routeDefinition.getId(),
-					routeDefinition.getFilters()));
+					new ArrayList<>(routeDefinition.getFilters())));
 		}
 
+		Flux.just().onErrorContinue()
 		AnnotationAwareOrderComparator.sort(filters);
 		return filters;
 	}