Empty form params should not be omitted (#340)

Author: deki

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/servlet/AwsHttpServletRequest.java

@@ -496,14 +496,16 @@ protected Map<String, List<String>> getFormUrlEncodedParametersMap() {
         urlEncodedFormParameters = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
         for (String parameter : rawBodyContent.split(FORM_DATA_SEPARATOR)) {
             String[] parameterKeyValue = parameter.split(HEADER_KEY_VALUE_SEPARATOR);
-            if (parameterKeyValue.length < 2) {
+            if (parameterKeyValue.length < 1) {
                 continue;
             }
             List<String> values = new ArrayList<>();
             if (urlEncodedFormParameters.containsKey(parameterKeyValue[0])) {
                 values = urlEncodedFormParameters.get(parameterKeyValue[0]);
             }
-            values.add(decodeValueIfEncoded(parameterKeyValue[1]));
+            if (parameterKeyValue.length > 1) {
+                values.add(decodeValueIfEncoded(parameterKeyValue[1]));
+            }
             urlEncodedFormParameters.put(decodeValueIfEncoded(parameterKeyValue[0]), values);
         }
         Timer.stop("SERVLET_REQUEST_GET_FORM_PARAMS");

aws-serverless-java-container-core/src/test/java/com/amazonaws/serverless/proxy/internal/servlet/AwsProxyHttpServletRequestFormTest.java

@@ -123,4 +123,21 @@ public void postForm_getParamsBase64Encoded_expectAllParams() {
         assertEquals(2, params.size());
         assertEquals(true, params.containsKey(PART_KEY_1));
     }
+
+    /**
+     * issue #340
+     */
+    @Test
+    public void postForm_emptyParamPresent() {
+        AwsProxyRequest proxyRequest = new AwsProxyRequestBuilder("/form", "POST")
+                .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_FORM_URLENCODED).build();
+        String body = PART_KEY_1 + "=" + "&" + PART_KEY_2 + "=" + PART_VALUE_2;
+        proxyRequest.setBody(body);
+
+        HttpServletRequest request = new AwsProxyHttpServletRequest(proxyRequest, null, null);
+        Map<String, String[]> params = request.getParameterMap();
+        assertNotNull(params);
+        assertEquals(2, params.size());
+        assertEquals(true, params.containsKey(PART_KEY_1));
+    }
 }