Allow types for HttpRequest.body to be either a string or a buffer (#3509)

* test httpRequest.body as string or buffer

* request body may be a string or a buffer

Looking at the source, it seems clear that the body of a request may be
either a string or a buffer.

https://github.com/aws/aws-sdk-js/blob/14e9bf0abab009e2f34f11623949375b7bd07d2a/lib/http/node.js#L115-L142

This commit fixes the types accordingly.

* add changelog json diff

Author: jeromecovington

.changes/next-release/bugfix-HttpRequest-0e36296c.json

@@ -0,0 +1,5 @@
+{
+  "type": "bugfix",
+  "category": "HttpRequest",
+  "description": "Allows request body to be either a string or a buffer"
+}

lib/http_request.d.ts

@@ -18,7 +18,7 @@ export class HttpRequest {
     /**
      * The request body payload.
      */
-    body: string;
+    body: string | Buffer;
     /**
      * The endpoint for the request.
      */

ts/request.ts

@@ -19,6 +19,11 @@ request.on('error', function(err, response) {
 
 });
 request.on('build', function(request) {
+    // test body as string
+    request.httpRequest.body = 'Hello'
+    // test body as buffer
+    request.httpRequest.body = Buffer.from('Hello')
+
     console.log(request.httpRequest.method);
 });
 request.on('complete', function(response) {