Fix nullable annotations on HttpClient.Post/Put/PatchAsync (#44880)

Null content is allowed.

Author: stephentoub

src/libraries/System.Net.Http/ref/System.Net.Http.cs

@@ -78,18 +78,18 @@ protected override void Dispose(bool disposing) { }
         public System.Threading.Tasks.Task<string> GetStringAsync(string? requestUri, System.Threading.CancellationToken cancellationToken) { throw null; }
         public System.Threading.Tasks.Task<string> GetStringAsync(System.Uri? requestUri) { throw null; }
         public System.Threading.Tasks.Task<string> GetStringAsync(System.Uri? requestUri, System.Threading.CancellationToken cancellationToken) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PatchAsync(string? requestUri, System.Net.Http.HttpContent content) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PatchAsync(string? requestUri, System.Net.Http.HttpContent content, System.Threading.CancellationToken cancellationToken) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PatchAsync(System.Uri? requestUri, System.Net.Http.HttpContent content) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PatchAsync(System.Uri? requestUri, System.Net.Http.HttpContent content, System.Threading.CancellationToken cancellationToken) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PostAsync(string? requestUri, System.Net.Http.HttpContent content) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PostAsync(string? requestUri, System.Net.Http.HttpContent content, System.Threading.CancellationToken cancellationToken) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PostAsync(System.Uri? requestUri, System.Net.Http.HttpContent content) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PostAsync(System.Uri? requestUri, System.Net.Http.HttpContent content, System.Threading.CancellationToken cancellationToken) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PutAsync(string? requestUri, System.Net.Http.HttpContent content) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PutAsync(string? requestUri, System.Net.Http.HttpContent content, System.Threading.CancellationToken cancellationToken) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PutAsync(System.Uri? requestUri, System.Net.Http.HttpContent content) { throw null; }
-        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PutAsync(System.Uri? requestUri, System.Net.Http.HttpContent content, System.Threading.CancellationToken cancellationToken) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PatchAsync(string? requestUri, System.Net.Http.HttpContent? content) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PatchAsync(string? requestUri, System.Net.Http.HttpContent? content, System.Threading.CancellationToken cancellationToken) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PatchAsync(System.Uri? requestUri, System.Net.Http.HttpContent? content) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PatchAsync(System.Uri? requestUri, System.Net.Http.HttpContent? content, System.Threading.CancellationToken cancellationToken) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PostAsync(string? requestUri, System.Net.Http.HttpContent? content) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PostAsync(string? requestUri, System.Net.Http.HttpContent? content, System.Threading.CancellationToken cancellationToken) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PostAsync(System.Uri? requestUri, System.Net.Http.HttpContent? content) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PostAsync(System.Uri? requestUri, System.Net.Http.HttpContent? content, System.Threading.CancellationToken cancellationToken) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PutAsync(string? requestUri, System.Net.Http.HttpContent? content) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PutAsync(string? requestUri, System.Net.Http.HttpContent? content, System.Threading.CancellationToken cancellationToken) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PutAsync(System.Uri? requestUri, System.Net.Http.HttpContent? content) { throw null; }
+        public System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> PutAsync(System.Uri? requestUri, System.Net.Http.HttpContent? content, System.Threading.CancellationToken cancellationToken) { throw null; }
         [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("browser")]
         public System.Net.Http.HttpResponseMessage Send(System.Net.Http.HttpRequestMessage request) { throw null; }
         [System.Runtime.Versioning.UnsupportedOSPlatformAttribute("browser")]

src/libraries/System.Net.Http/src/System/Net/Http/HttpClient.cs

@@ -376,48 +376,48 @@ public Task<HttpResponseMessage> GetAsync(string? requestUri, HttpCompletionOpti
         public Task<HttpResponseMessage> GetAsync(Uri? requestUri, HttpCompletionOption completionOption, CancellationToken cancellationToken) =>
             SendAsync(CreateRequestMessage(HttpMethod.Get, requestUri), completionOption, cancellationToken);
 
-        public Task<HttpResponseMessage> PostAsync(string? requestUri, HttpContent content) =>
+        public Task<HttpResponseMessage> PostAsync(string? requestUri, HttpContent? content) =>
             PostAsync(CreateUri(requestUri), content);
 
-        public Task<HttpResponseMessage> PostAsync(Uri? requestUri, HttpContent content) =>
+        public Task<HttpResponseMessage> PostAsync(Uri? requestUri, HttpContent? content) =>
             PostAsync(requestUri, content, CancellationToken.None);
 
-        public Task<HttpResponseMessage> PostAsync(string? requestUri, HttpContent content, CancellationToken cancellationToken) =>
+        public Task<HttpResponseMessage> PostAsync(string? requestUri, HttpContent? content, CancellationToken cancellationToken) =>
             PostAsync(CreateUri(requestUri), content, cancellationToken);
 
-        public Task<HttpResponseMessage> PostAsync(Uri? requestUri, HttpContent content, CancellationToken cancellationToken)
+        public Task<HttpResponseMessage> PostAsync(Uri? requestUri, HttpContent? content, CancellationToken cancellationToken)
         {
             HttpRequestMessage request = CreateRequestMessage(HttpMethod.Post, requestUri);
             request.Content = content;
             return SendAsync(request, cancellationToken);
         }
 
-        public Task<HttpResponseMessage> PutAsync(string? requestUri, HttpContent content) =>
+        public Task<HttpResponseMessage> PutAsync(string? requestUri, HttpContent? content) =>
             PutAsync(CreateUri(requestUri), content);
 
-        public Task<HttpResponseMessage> PutAsync(Uri? requestUri, HttpContent content) =>
+        public Task<HttpResponseMessage> PutAsync(Uri? requestUri, HttpContent? content) =>
             PutAsync(requestUri, content, CancellationToken.None);
 
-        public Task<HttpResponseMessage> PutAsync(string? requestUri, HttpContent content, CancellationToken cancellationToken) =>
+        public Task<HttpResponseMessage> PutAsync(string? requestUri, HttpContent? content, CancellationToken cancellationToken) =>
             PutAsync(CreateUri(requestUri), content, cancellationToken);
 
-        public Task<HttpResponseMessage> PutAsync(Uri? requestUri, HttpContent content, CancellationToken cancellationToken)
+        public Task<HttpResponseMessage> PutAsync(Uri? requestUri, HttpContent? content, CancellationToken cancellationToken)
         {
             HttpRequestMessage request = CreateRequestMessage(HttpMethod.Put, requestUri);
             request.Content = content;
             return SendAsync(request, cancellationToken);
         }
 
-        public Task<HttpResponseMessage> PatchAsync(string? requestUri, HttpContent content) =>
+        public Task<HttpResponseMessage> PatchAsync(string? requestUri, HttpContent? content) =>
             PatchAsync(CreateUri(requestUri), content);
 
-        public Task<HttpResponseMessage> PatchAsync(Uri? requestUri, HttpContent content) =>
+        public Task<HttpResponseMessage> PatchAsync(Uri? requestUri, HttpContent? content) =>
             PatchAsync(requestUri, content, CancellationToken.None);
 
-        public Task<HttpResponseMessage> PatchAsync(string? requestUri, HttpContent content, CancellationToken cancellationToken) =>
+        public Task<HttpResponseMessage> PatchAsync(string? requestUri, HttpContent? content, CancellationToken cancellationToken) =>
             PatchAsync(CreateUri(requestUri), content, cancellationToken);
 
-        public Task<HttpResponseMessage> PatchAsync(Uri? requestUri, HttpContent content, CancellationToken cancellationToken)
+        public Task<HttpResponseMessage> PatchAsync(Uri? requestUri, HttpContent? content, CancellationToken cancellationToken)
         {
             HttpRequestMessage request = CreateRequestMessage(HttpMethod.Patch, requestUri);
             request.Content = content;