Add modernize-java plugin

Added new plugin 'modernize-java' for Java modernization and upgrade assistance.

Author: leonard520

.github/plugin/marketplace.json

@@ -345,6 +345,29 @@
         "path": "plugins/modernize-dotnet"
       }
     },
+    {
+      "name": "modernize-java",
+      "description": "AI-powered Java modernization and upgrade assistant. Helps upgrade Java and Spring Boot applications to the latest versions.",
+      "version": "1.0.0",
+      "author": {
+        "name": "Microsoft",
+        "url": "https://www.microsoft.com"
+      },
+      "homepage": "https://github.com/microsoft/modernize-java",
+      "keywords": [
+        "modernization",
+        "upgrade",
+        "migration",
+        "java"
+      ],
+      "license": "MIT",
+      "repository": "https://github.com/microsoft/modernize-java",
+      "source": {
+        "source": "github",
+        "repo": "microsoft/modernize-java",
+        "path": "plugins/modernize-java"
+      }
+    },
     {
       "name": "napkin",
       "source": "napkin",

plugins/external.json

@@ -155,5 +155,23 @@
       "source": "github",
       "repo": "microsoft/What-I-Did-Copilot"
     }
+  },
+  {
+    "name": "modernize-java",
+    "description": "AI-powered Java modernization and upgrade assistant. Helps upgrade Java and Spring Boot applications to the latest versions.",
+    "version": "1.0.0",
+    "author": {
+      "name": "Microsoft",
+      "url": "https://www.microsoft.com"
+    },
+    "homepage": "https://github.com/microsoft/modernize-java",
+    "keywords": ["modernization", "upgrade", "migration", "java"],
+    "license": "MIT",
+    "repository": "https://github.com/microsoft/modernize-java",
+    "source": {
+      "source": "github",
+      "repo": "microsoft/modernize-java",
+      "path": "plugins/modernize-java"
+    }
   }
 ]