check null before use this.content

Resolves #1192
Resolves #1193

Author: npeters

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/main/java/org/springframework/cloud/function/serverless/web/ServerlessHttpServletRequest.java

@@ -77,6 +77,7 @@ public class ServerlessHttpServletRequest implements HttpServletRequest {
 
 	private static final BufferedReader EMPTY_BUFFERED_READER = new BufferedReader(new StringReader(""));
 
+	private static final InputStream EMPTY_INPUT_STREAM = new ByteArrayInputStream(new byte[0]);
 	/**
 	 * Date formats as specified in the HTTP RFC.
 	 *
@@ -283,7 +284,15 @@ public String getContentType() {
 
 	@Override
 	public ServletInputStream getInputStream() {
-		InputStream stream = new ByteArrayInputStream(this.content);
+
+		InputStream stream;
+		if (this.content == null) {
+			stream = EMPTY_INPUT_STREAM;
+		}
+		else {
+			stream = new ByteArrayInputStream(this.content);
+		}
+
 		return new ServletInputStream() {
 
 			boolean finished = false;

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/test/java/org/springframework/cloud/function/serverless/web/RequestResponseTests.java

@@ -149,6 +149,21 @@ public void validatePostWithBody() throws Exception {
 		assertThat(pet.getName()).isNotEmpty();
 	}
 
+	@Test
+	public void validatePostWithoutBody() throws Exception {
+		ServerlessHttpServletRequest request = new ServerlessHttpServletRequest(null, "POST", "/pets/");
+		request.setContentType("application/json");
+		ServerlessHttpServletResponse response = new ServerlessHttpServletResponse();
+		try {
+			mvc.service(request, response);
+		}
+		catch (jakarta.servlet.ServletException e) {
+			assertThat(e.getCause()).isNotInstanceOf(NullPointerException.class);
+		}
+
+		assertThat(response.getStatus()).isEqualTo(400); // application fail because the pet is empty ;)
+	}
+
 	@Test
 	public void validatePostAsyncWithBody() throws Exception {
 //		System.setProperty("spring.main.banner-mode", "off");