Polish and fix test

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/http/client/ReactorHttpClientBuilder.java

@@ -61,7 +61,8 @@ public final class ReactorHttpClientBuilder {
 	 */
 	public ReactorHttpClientBuilder withHttpClientCustomizer(UnaryOperator<HttpClient> customizer) {
 		Assert.notNull(customizer, "'customizer' must not be null");
-		return new ReactorHttpClientBuilder((t) -> customizer.apply(this.customizer.apply(t)));
+		return new ReactorHttpClientBuilder(this.factory,
+				(httpClient) -> customizer.apply(this.customizer.apply(httpClient)));
 	}
 
 	/**

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/http/client/reactive/ReactorClientHttpConnectorBuilderTests.java

@@ -55,7 +55,7 @@ class ReactorClientHttpConnectorBuilderTests
 			httpClients.add(httpClient);
 			return httpClient;
 		};
-		ClientHttpRequestFactoryBuilder.reactor()
+		ClientHttpConnectorBuilder.reactor()
 			.withHttpClientCustomizer(httpClientCustomizer1)
 			.withHttpClientCustomizer(httpClientCustomizer2)
 			.build();