test(build): load Java plugin companion plugins in 262 test sandbox

On 262 the plugin-java tests failed with the Java plugin's services
missing: JavaDirectoryService.getInstance() returned null,
ProjectJdkTable could not be cast to JavaAwareProjectJdkTableImpl, and
JarApplicationConfigurationType was not a registered run-config type.

Root cause: the whole 'Java' plugin was excluded from the test sandbox
because several bundled plugins it depends on (structure view, bookmarks,
test runner, todo, structural search, misc libraries, copyright, terminal,
XPath) were not present, and the Gradle plugin no longer resolves the
transitive bundled-plugin dependencies of a bundledPlugin() automatically
since 2.4.0 (JetBrains/intellij-platform-gradle-plugin#1930). Once a
required content module cannot resolve, the entire Java plugin — including
its impl/execution/backend modules that register those services — is
dropped.

There is no catch-all or "full IDE" test mode, so declare the companion
plugins explicitly. Kept as a single documented list (javaTestCompanionPlugins)
and guarded to platformVersion >= 262 so 251 is untouched.

Verified: full :plugin-java:test passes on both 251 and 262.

Assisted-by: Claude:claude-opus-4-8

Author: dividedmind

build.gradle.kts

@@ -45,6 +45,24 @@ version = pluginVersionString
 
 val platformVersion = prop("platformVersion").toInt()
 
+// Bundled plugins that com.intellij.java requires but that the Gradle plugin no longer pulls in
+// transitively (JetBrains/intellij-platform-gradle-plugin#1930), so the Java plugin is excluded from
+// the 262+ test sandbox and its services (JavaDirectoryService, JavaAwareProjectJdkTable, run-config
+// types) never register. There is no catch-all/"full IDE" test mode, so we list them explicitly.
+// To refresh after a platform bump: run tests, look for "'Java' ... excluded" / "X is not resolved"
+// in the sandbox log, and add the plugin owning module X (`printBundledPlugins` lists the IDs).
+val javaTestCompanionPlugins = listOf(
+    "intellij.structureView.plugin",
+    "intellij.bookmarks.plugin",
+    "intellij.testRunner.plugin",
+    "intellij.todo.plugin",
+    "intellij.structuralSearch.plugin",
+    "intellij.libraries.misc.plugin",
+    "com.intellij.copyright",
+    "org.jetbrains.plugins.terminal",
+    "XPathView",
+)
+
 val isCI = System.getenv("CI") == "true"
 val agentOutputPath = rootProject.layout.buildDirectory.asFile.get()
     .resolve("appmap-java-agent")
@@ -479,6 +497,10 @@ project(":plugin-java") {
         intellijPlatform {
             bundledPlugin("com.intellij.java")
             bundledPlugin("com.intellij.properties")
+            // see javaTestCompanionPlugins
+            if (platformVersion >= 262) {
+                bundledPlugins(javaTestCompanionPlugins)
+            }
         }
     }
 }