fixes #96 HeaderMiddleware cannot add new headers from header.yml

Author: stevehu

src/main/java/com/networknt/aws/lambda/handler/middleware/header/HeaderMiddleware.java

@@ -80,13 +80,24 @@ public void updateHeaders(Map<String, Object> updateMap, Map<String, String> hea
         for (Map.Entry<String, Object> entry : updateMap.entrySet()) {
             lowercaseUpdateMap.put(entry.getKey().toLowerCase(), entry.getValue());
         }
-        // Iterate over the original map and update values where keys match case-insensitively
+        // Iterate over the original header map and update values where keys match case-insensitively
         for (Map.Entry<String, String> entry : headers.entrySet()) {
             String lowercaseKey = entry.getKey().toLowerCase();
             if (lowercaseUpdateMap.containsKey(lowercaseKey)) {
                 headers.put(entry.getKey(), (String)lowercaseUpdateMap.get(lowercaseKey));
             }
         }
-
+        // convert the headers map to lowercase
+        Map<String, String> lowercaseHeaders = new HashMap<>();
+        for (Map.Entry<String, String> entry : headers.entrySet()) {
+            lowercaseHeaders.put(entry.getKey().toLowerCase(), entry.getValue());
+        }
+        // Iterate over the update map and add new entries to the header map
+        for (Map.Entry<String, Object> entry : updateMap.entrySet()) {
+            String lowercaseKey = entry.getKey().toLowerCase();
+            if (!lowercaseHeaders.containsKey(lowercaseKey)) {
+                headers.put(entry.getKey(), (String)entry.getValue());
+            }
+        }
     }
 }

src/test/java/com/networknt/aws/lambda/middleware/header/ResponseHeaderMiddlewareTest.java

@@ -40,5 +40,9 @@ void testResponseHeaderRemoveUpdate() {
         // headerC and headerD should be removed by the /v1/pets rule.
         Assertions.assertTrue(MapUtil.getValueIgnoreCase(responseEvent.getHeaders(), "headerC").isEmpty());
         Assertions.assertTrue(MapUtil.getValueIgnoreCase(responseEvent.getHeaders(), "headerD").isEmpty());
+
+        // keyC and KeyD should be added by the /v1/pets rule.
+        Assertions.assertEquals("valueC", responseEvent.getHeaders().get("keyC"));  // lower case
+        Assertions.assertEquals("valueD", responseEvent.getHeaders().get("KeyD"));  // upper case
     }
 }

src/test/java/com/networknt/aws/lambda/middleware/proxy/MockLambdaProxyMiddleware.java

@@ -75,8 +75,6 @@ private String invokeFunction(final LambdaClient client, String functionName, fi
         headers.put("Content-Type", "application/json");
         headers.put("Key3", "oldValue3");
         headers.put("key4", "oldValue4");
-        headers.put("KeyC", "oldValueC");
-        headers.put("keyD", "oldValueD");
         headers.put("header3", "value3");
         headers.put("Header4", "value4");
         headers.put("headerC", "valueC");

src/test/resources/config/values.yml

@@ -62,7 +62,7 @@ header.pathPrefixHeader:
         - headerD
       update:
         keyC: valueC
-        keyD: valueD
+        KeyD: valueD
 
 # handler.yml
 handler.handlers: