Fix NPE for null in the query parameters

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

@@ -529,7 +529,9 @@ public String getParameter(String s) {
     @Override
     public Enumeration<String> getParameterNames() {
         List<String> paramNames = new ArrayList<>();
-        paramNames.addAll(request.getQueryStringParameters().keySet());
+        if (request.getQueryStringParameters() != null) {
+            paramNames.addAll(request.getQueryStringParameters().keySet());
+        }
         paramNames.addAll(urlEncodedFormParameters.keySet());
         return Collections.enumeration(paramNames);
     }
@@ -567,13 +569,15 @@ public Map<String, String[]> getParameterMap() {
             params = new HashMap<>();
         }
 
-        for (Map.Entry<String, String> entry : request.getQueryStringParameters().entrySet()) {
-            if (params.containsKey(entry.getKey())) {
-                params.get(entry.getKey()).add(entry.getValue());
-            } else {
-                List<String> valueList = new ArrayList<>();
-                valueList.add(entry.getValue());
-                params.put(entry.getKey(), valueList);
+        if (request.getQueryStringParameters() != null) {
+            for (Map.Entry<String, String> entry : request.getQueryStringParameters().entrySet()) {
+                if (params.containsKey(entry.getKey())) {
+                    params.get(entry.getKey()).add(entry.getValue());
+                } else {
+                    List<String> valueList = new ArrayList<>();
+                    valueList.add(entry.getValue());
+                    params.put(entry.getKey(), valueList);
+                }
             }
         }
 

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

@@ -8,6 +8,10 @@
 import javax.ws.rs.core.HttpHeaders;
 import javax.ws.rs.core.MediaType;
 
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.List;
+
 import static org.junit.Assert.*;
 
 public class AwsProxyHttpServletRequestTest {
@@ -39,6 +43,16 @@ public class AwsProxyHttpServletRequestTest {
     private static final AwsProxyRequest REQUEST_MALFORMED_COOKIE = new AwsProxyRequestBuilder("/hello", "GET")
             .header(HttpHeaders.COOKIE, QUERY_STRING_NAME_VALUE).build();
 
+    private static final AwsProxyRequest REQUEST_NULL_QUERY_STRING;
+    static {
+        AwsProxyRequest awsProxyRequest = new AwsProxyRequestBuilder("/hello", "GET").build();
+        awsProxyRequest.setQueryStringParameters(null);
+        REQUEST_NULL_QUERY_STRING = awsProxyRequest;
+    }
+
+    private static final AwsProxyRequest REQUEST_QUERY = new AwsProxyRequestBuilder("/hello", "POST")
+            .queryString(FORM_PARAM_NAME, QUERY_STRING_NAME_VALUE).build();
+
 
     @Test
     public void headers_getHeader_validRequest() {
@@ -131,4 +145,36 @@ public void cookie_getCookies_emptyCookies() {
         assertNotNull(request.getCookies());
         assertEquals(0, request.getCookies().length);
     }
+
+    @Test
+    public void queryParameters_getParameterMap_null() {
+        HttpServletRequest request = new AwsProxyHttpServletRequest(REQUEST_NULL_QUERY_STRING, null, null);
+        assertNotNull(request);
+        assertEquals(0, request.getParameterMap().size());
+    }
+
+    @Test
+    public void queryParameters_getParameterMap_nonNull() {
+        HttpServletRequest request = new AwsProxyHttpServletRequest(REQUEST_QUERY, null, null);
+        assertNotNull(request);
+        assertEquals(1, request.getParameterMap().size());
+        assertEquals(QUERY_STRING_NAME_VALUE, request.getParameterMap().get(FORM_PARAM_NAME)[0]);
+    }
+
+    @Test
+    public void queryParameters_getParameterNames_null() {
+        HttpServletRequest request = new AwsProxyHttpServletRequest(REQUEST_NULL_QUERY_STRING, null, null);
+        List<String> parameterNames = Collections.list(request.getParameterNames());
+        assertNotNull(request);
+        assertEquals(0, parameterNames.size());
+    }
+
+    @Test
+    public void queryParameters_getParameterNames_nonNull() {
+        HttpServletRequest request = new AwsProxyHttpServletRequest(REQUEST_QUERY, null, null);
+        List<String> parameterNames = Collections.list(request.getParameterNames());
+        assertNotNull(request);
+        assertEquals(1, parameterNames.size());
+        assertTrue(parameterNames.contains(FORM_PARAM_NAME));
+    }
 }