Consistent headers.getContentLength() checks

(cherry picked from commit 7f438dc)

spring-web/src/main/java/org/springframework/http/client/AbstractBufferingAsyncClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,7 @@ abstract class AbstractBufferingAsyncClientHttpRequest extends AbstractAsyncClie
 	@Override
 	protected ListenableFuture<ClientHttpResponse> executeInternal(HttpHeaders headers) throws IOException {
 		byte[] bytes = this.bufferedOutput.toByteArray();
-		if (headers.getContentLength() == -1) {
+		if (headers.getContentLength() < 0) {
 			headers.setContentLength(bytes.length);
 		}
 		ListenableFuture<ClientHttpResponse> result = executeInternal(headers, bytes);

spring-web/src/main/java/org/springframework/http/client/AbstractBufferingClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,7 +42,7 @@ abstract class AbstractBufferingClientHttpRequest extends AbstractClientHttpRequ
 	@Override
 	protected ClientHttpResponse executeInternal(HttpHeaders headers) throws IOException {
 		byte[] bytes = this.bufferedOutput.toByteArray();
-		if (headers.getContentLength() == -1) {
+		if (headers.getContentLength() < 0) {
 			headers.setContentLength(bytes.length);
 		}
 		ClientHttpResponse result = executeInternal(headers, bytes);

spring-web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java

@@ -132,7 +132,7 @@ public class ServletServerHttpRequest implements ServerHttpRequest {
 					this.headers.setContentType(newContentType);
 				}
 			}
-			if (this.headers.getContentLength() == -1) {
+			if (this.headers.getContentLength() < 0) {
 				int requestContentLength = this.servletRequest.getContentLength();
 				if (requestContentLength != -1) {
 					this.headers.setContentLength(requestContentLength);

spring-web/src/main/java/org/springframework/web/client/RestTemplate.java

@@ -780,7 +780,7 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 				if (!requestHeaders.isEmpty()) {
 					httpHeaders.putAll(requestHeaders);
 				}
-				if (httpHeaders.getContentLength() == -1) {
+				if (httpHeaders.getContentLength() < 0) {
 					httpHeaders.setContentLength(0L);
 				}
 			}