Add negative test for name mapping

ballerina-tests/http-misc-tests/tests/http_header_test.bal

@@ -277,14 +277,21 @@ function testPassthruWithBody() returns error? {
 }
 
 type Headers record {|
-    @http:Header { name: "X-API-VERSION" }
+    @http:Header {name: "X-API-VERSION"}
     string apiVersion;
-    @http:Header { name: "X-REQ-ID" }
+    @http:Header {name: "X-REQ-ID"}
     int reqId;
-    @http:Header { name: "X-IDS" }
+    @http:Header {name: "X-IDS"}
     float[] ids;
 |};
 
+type HeadersNegative record {|
+    @http:Header
+    string header1;
+    @http:Header {name: ()}
+    string header2;
+|};
+
 @test:Config {}
 function testGetHeadersMethod() {
     Headers headers = {apiVersion: "v1", reqId: 123, ids: [1.0, 2.0, 3.0]};
@@ -296,6 +303,12 @@ function testGetHeadersMethod() {
     test:assertEquals(http:getHeaderMap(headers), expectedHeaderMap, "Header map is not as expected");
 }
 
+@test:Config {}
+function testGetHeadersMethodNegative() {
+    HeadersNegative headers = {header1: "header1", header2: "header2"};
+    test:assertEquals(http:getHeaderMap(headers), headers, "Header map is not as expected");
+}
+
 type Queries record {|
     @http:Query { name: "XName" }
     string name;