fix(common): add right ContentType for boolean values with HttpClient…

… request body(angular#38924)

currently a boolean as body is seen as text/plain, where is should be seen as application/json, since it is valid JSON, like numbers.

packages/common/http/src/request.ts

@@ -323,7 +323,7 @@ export class HttpRequest<T> {
       return 'application/x-www-form-urlencoded;charset=UTF-8';
     }
     // Arrays, objects, and numbers will be encoded as JSON.
-    if (typeof this.body === 'object' || typeof this.body === 'number' ||
+    if (typeof this.body === 'object' || typeof this.body === 'number' || typeof this.body === 'boolean' ||
         Array.isArray(this.body)) {
       return 'application/json';
     }

packages/common/http/test/request_spec.ts

@@ -129,6 +129,10 @@ const TEST_STRING = `I'm a body!`;
         const req = baseReq.clone({body: {data: 'test data'}});
         expect(req.detectContentTypeHeader()).toBe('application/json');
       });
+      it('handles boolean as json', () => {
+        const req = baseReq.clone({body: true});
+        expect(req.detectContentTypeHeader()).toBe('application/json');
+      });
     });
     describe('body serialization', () => {
       const baseReq = new HttpRequest('POST', '/test', null);