Fix content type when missing from incoming request

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/SimpleHostRoutingFilter.java

@@ -258,7 +258,8 @@ public class SimpleHostRoutingFilter extends ZuulFilter {
 		HttpRequest httpRequest;
 		int contentLength = request.getContentLength();
 		InputStreamEntity entity = new InputStreamEntity(requestEntity, contentLength,
-				ContentType.create(request.getContentType()));
+				request.getContentType() != null
+						? ContentType.create(request.getContentType()) : null);
 		switch (verb.toUpperCase()) {
 		case "POST":
 			HttpPost httpPost = new HttpPost(uri + this.helper.getQueryString(params));

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/zuul/SampleZuulProxyApplicationTests.java

@@ -158,6 +158,17 @@ public class SampleZuulProxyApplicationTests extends ZuulProxyTestBase {
 	}
 
 	@Test
+	public void simpleHostRouteWithContentType() {
+		this.routes.addRoute("/self/**", "http://localhost:" + this.port + "/");
+		this.endpoint.reset();
+		ResponseEntity<String> result = new TestRestTemplate().exchange(
+				"http://localhost:" + this.port + "/self/content-type", HttpMethod.POST,
+				new HttpEntity<>((Void) null), String.class);
+		assertEquals(HttpStatus.OK, result.getStatusCode());
+		assertEquals("<NONE>", result.getBody());
+	}
+
+	@Test
 	public void ribbonCommandForbidden() {
 		ResponseEntity<String> result = new TestRestTemplate().exchange(
 				"http://localhost:" + this.port + "/simple/throwexception/403",
@@ -223,6 +234,12 @@ class SampleZuulProxyApplication extends ZuulProxyTestBase.AbstractZuulProxyAppl
 		return request.getRequestURI();
 	}
 
+	@RequestMapping("/content-type")
+	public String contentType(HttpServletRequest request) {
+		String header = request.getHeader("Content-Type");
+		return header == null ? "<NONE>" : header;
+	}
+
 	@RequestMapping("/add-header")
 	public ResponseEntity<String> addHeader(HttpServletRequest request) {
 		HttpHeaders headers = new HttpHeaders();