Issue #4505 Ensure get/setInitParam with null arg throws NPE (#4509)

* Issue #4505 Ensure get/setInitParam with null arg throws NPE

jetty-servlet/src/main/java/org/eclipse/jetty/servlet/ServletContextHandler.java

@@ -28,6 +28,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
@@ -1287,6 +1288,14 @@ public class ServletContextHandler extends ContextHandler
                 return null; //existing completed registration for servlet name
         }
 
+        @Override
+        public String getInitParameter(String name)
+        {
+            //since servlet spec 4.0
+            Objects.requireNonNull(name);
+            return super.getInitParameter(name);
+        }
+
         @Override
         public boolean setInitParameter(String name, String value)
         {
@@ -1296,6 +1305,9 @@ public class ServletContextHandler extends ContextHandler
             if (!_enabled)
                 throw new UnsupportedOperationException();
 
+            //since servlet spec 4.0
+            Objects.requireNonNull(name);
+
             return super.setInitParameter(name, value);
         }
 

jetty-servlet/src/test/java/org/eclipse/jetty/servlet/ServletContextHandlerTest.java

@@ -87,6 +87,7 @@ import org.hamcrest.Matchers;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.function.Executable;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
@@ -97,6 +98,7 @@ import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
@@ -470,6 +472,32 @@ public class ServletContextHandlerTest
         _server.join();
     }
     
+    @Test
+    public void testInitParams() throws Exception
+    {
+        //Test get/setInitParam with null throws NPE
+        ServletContextHandler root = new ServletContextHandler(_server, "/", ServletContextHandler.SESSIONS);
+        _server.setHandler(root);
+        ListenerHolder initialListener = new ListenerHolder();
+        initialListener.setListener(new ServletContextListener()
+        {
+            public void contextInitialized(ServletContextEvent sce)
+            {
+                sce.getServletContext().setInitParameter("foo", "bar");
+                assertEquals("bar", sce.getServletContext().getInitParameter("foo"));
+                assertThrows(NullPointerException.class, 
+                    () ->  sce.getServletContext().setInitParameter(null, "bad")
+                );
+                assertThrows(NullPointerException.class,
+                    () -> sce.getServletContext().getInitParameter(null)
+                );
+            }
+        });
+        
+        root.getServletHandler().addListener(initialListener);
+        _server.start();
+    }
+    
     @Test
     public void testGetSetSessionTimeout() throws Exception
     {