8344361: Restore null return for invalid services from legacy providers

Reviewed-by: valeriep

src/java.base/share/classes/java/security/Provider.java

@@ -1147,6 +1147,7 @@ public abstract class Provider extends Properties {
             s = legacyMap.get(key);
             if (s != null && !s.isValid()) {
                 legacyMap.remove(key, s);
+                return null;
             }
         }
 

test/jdk/java/security/Provider/InvalidServiceTest.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8344361
+ * @summary Restore null return for invalid services
+ */
+
+import java.security.Provider;
+
+public class InvalidServiceTest {
+
+    public static void main(String[] args) throws Exception {
+        Provider p1 = new LProvider("LegacyFormat");
+        // this returns a service with null class name. Helps exercise the code path
+        Provider.Service s1 = p1.getService("MessageDigest", "SHA-1");
+        if (s1 != null)
+            throw new RuntimeException("expecting null service");
+    }
+
+    private static class LProvider extends Provider {
+        LProvider(String name) {
+            super(name, "1.0", null);
+            put("Signature.MD5withRSA", "com.foo.Sig");
+            put("MessageDigest.SHA-1 ImplementedIn", "Software");
+        }
+    }
+}