Updated tests for framework changes

Author: spencergibb

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/headers/ForwardedHeadersFilter.java

@@ -92,7 +92,8 @@ public int getOrder() {
 	@Override
 	public HttpHeaders filter(HttpHeaders input, ServerWebExchange exchange) {
 		ServerHttpRequest request = exchange.getRequest();
-		HttpHeaders original = input;
+		HttpHeaders original = new HttpHeaders();
+		original.putAll(input);
 		HttpHeaders updated = new HttpHeaders();
 
 		// copy all headers except Forwarded