Nullable HttpMethod parameter only on internal doExecute delegate

Issue: SPR-15540

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

@@ -655,23 +655,19 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 	public <T> ResponseEntity<T> exchange(RequestEntity<?> requestEntity, Class<T> responseType)
 			throws RestClientException {
 
-		Assert.notNull(requestEntity, "RequestEntity must not be null");
-
 		RequestCallback requestCallback = httpEntityCallback(requestEntity, responseType);
 		ResponseExtractor<ResponseEntity<T>> responseExtractor = responseEntityExtractor(responseType);
-		return nonNull(execute(requestEntity.getUrl(), requestEntity.getMethod(), requestCallback, responseExtractor));
+		return nonNull(doExecute(requestEntity.getUrl(), requestEntity.getMethod(), requestCallback, responseExtractor));
 	}
 
 	@Override
 	public <T> ResponseEntity<T> exchange(RequestEntity<?> requestEntity, ParameterizedTypeReference<T> responseType)
 			throws RestClientException {
 
-		Assert.notNull(requestEntity, "RequestEntity must not be null");
-
 		Type type = responseType.getType();
 		RequestCallback requestCallback = httpEntityCallback(requestEntity, type);
 		ResponseExtractor<ResponseEntity<T>> responseExtractor = responseEntityExtractor(type);
-		return nonNull(execute(requestEntity.getUrl(), requestEntity.getMethod(), requestCallback, responseExtractor));
+		return nonNull(doExecute(requestEntity.getUrl(), requestEntity.getMethod(), requestCallback, responseExtractor));
 	}
 
 
@@ -698,7 +694,7 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 
 	@Override
 	@Nullable
-	public <T> T execute(URI url, @Nullable HttpMethod method, @Nullable RequestCallback requestCallback,
+	public <T> T execute(URI url, HttpMethod method, @Nullable RequestCallback requestCallback,
 			@Nullable ResponseExtractor<T> responseExtractor) throws RestClientException {
 
 		return doExecute(url, method, requestCallback, responseExtractor);
@@ -718,8 +714,8 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 	protected <T> T doExecute(URI url, @Nullable HttpMethod method, @Nullable RequestCallback requestCallback,
 			@Nullable ResponseExtractor<T> responseExtractor) throws RestClientException {
 
-		Assert.notNull(url, "'url' must not be null");
-		Assert.notNull(method, "'method' must not be null");
+		Assert.notNull(url, "URI is required");
+		Assert.notNull(method, "HttpMethod is required");
 		ClientHttpResponse response = null;
 		try {
 			ClientHttpRequest request = createRequest(url, method);
@@ -728,12 +724,7 @@ public class RestTemplate extends InterceptingHttpAccessor implements RestOperat
 			}
 			response = request.execute();
 			handleResponse(url, method, response);
-			if (responseExtractor != null) {
-				return responseExtractor.extractData(response);
-			}
-			else {
-				return null;
-			}
+			return (responseExtractor != null ? responseExtractor.extractData(response) : null);
 		}
 		catch (IOException ex) {
 			String resource = url.toString();