Consistently remove forwarded headers in WebFlux

Preparation for SPR-17072

Author: rstoyanchev

spring-web/src/main/java/org/springframework/web/filter/reactive/ForwardedHeaderFilter.java

@@ -91,6 +91,7 @@ public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
 							builder.path(prefix + uri.getPath());
 							builder.contextPath(prefix);
 						}
+						removeForwardedHeaders(builder);
 					})
 					.build();
 		}

spring-web/src/test/java/org/springframework/web/filter/reactive/ForwardedHeaderFilterTests.java

@@ -74,6 +74,7 @@ public void xForwardedHeaders() throws Exception {
 		this.filter.filter(getExchange(headers), this.filterChain).block(Duration.ZERO);
 
 		assertEquals(new URI("https://84.198.58.199/path"), this.filterChain.uri);
+		this.filterChain.assertForwardedHeadersRemoved();
 	}
 
 	@Test
@@ -83,6 +84,7 @@ public void forwardedHeader() throws Exception {
 		this.filter.filter(getExchange(headers), this.filterChain).block(Duration.ZERO);
 
 		assertEquals(new URI("https://84.198.58.199/path"), this.filterChain.uri);
+		this.filterChain.assertForwardedHeadersRemoved();
 	}
 
 	@Test
@@ -93,6 +95,7 @@ public void xForwardedPrefix() throws Exception {
 
 		assertEquals(new URI("http://example.com/prefix/path"), this.filterChain.uri);
 		assertEquals("/prefix/path", this.filterChain.requestPathValue);
+		this.filterChain.assertForwardedHeadersRemoved();
 	}
 
 	@Test
@@ -103,6 +106,7 @@ public void xForwardedPrefixTrailingSlash() throws Exception {
 
 		assertEquals(new URI("http://example.com/prefix/path"), this.filterChain.uri);
 		assertEquals("/prefix/path", this.filterChain.requestPathValue);
+		this.filterChain.assertForwardedHeadersRemoved();
 	}
 
 	private MockServerWebExchange getExchange(HttpHeaders headers) {