Add external plugin modernize-java (#1997)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

.github/plugin/marketplace.json

@@ -581,6 +581,31 @@
         "path": "plugins/modernize-dotnet"
       }
     },
+    {
+      "name": "modernize-java",
+      "description": "GitHub Copilot modernization – Java Upgrade CLI Plugin helps you upgrade Java applications from the command line. It brings intelligent modernization capabilities to your terminal and CI/CD pipelines: analyze your project and generate an upgrade plan, automatically transform your codebase, fix build issues, validate against known CVEs, and output a detailed summary of file changes and updated dependencies.",
+      "version": "1.9.2",
+      "author": {
+        "name": "microsoft",
+        "url": "https://github.com/microsoft/modernize-java"
+      },
+      "repository": "https://github.com/microsoft/modernize-java",
+      "homepage": "https://github.com/microsoft/modernize-java",
+      "license": "MIT",
+      "keywords": [
+        "java",
+        "modernization",
+        "upgrade",
+        "spring-boot"
+      ],
+      "source": {
+        "source": "github",
+        "repo": "microsoft/modernize-java",
+        "path": "plugins/modernize-java",
+        "ref": "1.9.2",
+        "sha": "b570196c070bf1eb9d7ad34a263b228ef16034a0"
+      }
+    },
     {
       "name": "napkin",
       "source": "napkin",

plugins/external.json

@@ -390,6 +390,31 @@
       "path": "plugins/modernize-dotnet"
     }
   },
+  {
+    "name": "modernize-java",
+    "description": "GitHub Copilot modernization – Java Upgrade CLI Plugin helps you upgrade Java applications from the command line. It brings intelligent modernization capabilities to your terminal and CI/CD pipelines: analyze your project and generate an upgrade plan, automatically transform your codebase, fix build issues, validate against known CVEs, and output a detailed summary of file changes and updated dependencies.",
+    "version": "1.9.2",
+    "author": {
+      "name": "microsoft",
+      "url": "https://github.com/microsoft/modernize-java"
+    },
+    "repository": "https://github.com/microsoft/modernize-java",
+    "homepage": "https://github.com/microsoft/modernize-java",
+    "license": "MIT",
+    "keywords": [
+      "java",
+      "modernization",
+      "upgrade",
+      "spring-boot"
+    ],
+    "source": {
+      "source": "github",
+      "repo": "microsoft/modernize-java",
+      "path": "plugins/modernize-java",
+      "ref": "1.9.2",
+      "sha": "b570196c070bf1eb9d7ad34a263b228ef16034a0"
+    }
+  },
   {
     "name": "pm-skills",
     "description": "MCP server and 12 skills for product analysis, specification writing, strategy, narrative, and stakeholder alignment. Run competitive analyses, write zero-question specs, design metrics, and produce executive-ready documents directly from Copilot.",