GH-489 the received data which Post Flux data to FunctionController is not same as the function apply

fix test case

spring-cloud-function-samples/function-sample/src/test/java/com/example/WebTestClientTests.java

@@ -0,0 +1,62 @@
+package com.example;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
+import org.springframework.cloud.function.context.test.FunctionalSpringBootTest;
+import org.springframework.http.MediaType;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.reactive.server.WebTestClient;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@RunWith(SpringRunner.class)
+@FunctionalSpringBootTest
+@AutoConfigureWebTestClient
+public class WebTestClientTests {
+
+	@Autowired
+	private WebTestClient client;
+
+	@Test
+	public void uppercase() {
+		client.post().uri("/uppercase").body(Mono.just("foo"), String.class).exchange()
+				.expectStatus().isOk().expectBody(String.class).isEqualTo("FOO");
+	}
+
+	@Test
+	public void lowercase() {
+		client.post().uri("/lowercase").body(Flux.just("FOO", "BAR"), String.class).exchange()
+				.expectStatus().isOk().expectBody(String.class).isEqualTo("[\"foobar\"]");
+	}
+
+	@Test
+	public void testStream() {
+
+		List<String> asObjectExpect = new ArrayList<>();
+		asObjectExpect.add("foobar");
+
+		//as object
+		client.post().uri("/lowercase").accept(MediaType.TEXT_EVENT_STREAM).body(Flux.just("FOO", "BAR"), String.class)
+				.exchange().expectBodyList(String.class).isEqualTo(asObjectExpect);
+
+		List<String> asFluxExpect = new ArrayList<>();
+		asFluxExpect.add("foo");
+		asFluxExpect.add("bar");
+
+		//as flux
+		client.post().uri("/lowercase").accept(MediaType.TEXT_EVENT_STREAM).body(Flux.just("FOO\n", "BAR\n"), String.class)
+			.exchange().expectBodyList(String.class).isEqualTo(asFluxExpect);
+	}
+
+	@Test
+	public void testCollection() {
+		client.post().uri("/lowercase").contentType(MediaType.APPLICATION_JSON).body(Mono.just("[\"FOO\",  \"BAR\"]"), String.class)
+				.exchange().expectBody(String.class).isEqualTo("[\"foo\",\"bar\"]");
+	}
+
+}