[plugin model] refactoring: get rid of unnecessary base class 'ContentElement'

The only allowed element in the `content` tag is a `module`, and we don't plan to introduce other elements there. So to simplify code, `ContentElement.Module` is renamed to `ContentModuleElement`, and usages of its base class are inlined.

GitOrigin-RevId: db53095675961b35aac09b6ff9d61d0120db1d86

platform/core-impl/src/com/intellij/ide/plugins/IdeaPluginDescriptorImpl.kt

@@ -475,21 +475,13 @@ class PluginMainDescriptor(
 
   @ApiStatus.Internal
   companion object {
-    private fun convertContentModules(contentElements: List<ContentElement>): List<PluginContentDescriptor.ModuleItem> {
-      return contentElements.mapNotNull { elem ->
-        when (elem) {
-          is ContentElement.Module -> {
-            val index = elem.name.lastIndexOf('/')
-            val configFile: String? = if (index != -1) {
-              "${elem.name.substring(0, index)}.${elem.name.substring(index + 1)}.xml"
-            } else null
-            PluginContentDescriptor.ModuleItem(elem.name, configFile, elem.embeddedDescriptorContent, elem.loadingRule.convert())
-          }
-          else -> {
-            LOG.error("Unknown content element: $elem")
-            null
-          }
-        }
+    private fun convertContentModules(contentElements: List<ContentModuleElement>): List<PluginContentDescriptor.ModuleItem> {
+      return contentElements.map { elem ->
+        val index = elem.name.lastIndexOf('/')
+        val configFile: String? = if (index != -1) {
+          "${elem.name.substring(0, index)}.${elem.name.substring(index + 1)}.xml"
+        } else null
+        PluginContentDescriptor.ModuleItem(elem.name, configFile, elem.embeddedDescriptorContent, elem.loadingRule.convert())
       }
     }
     

platform/platform-tests/testSrc/com/intellij/ide/plugins/PluginModelValidator.kt

@@ -7,7 +7,7 @@ import com.fasterxml.jackson.core.JsonFactory
 import com.fasterxml.jackson.core.JsonGenerator
 import com.intellij.openapi.extensions.PluginId
 import com.intellij.platform.plugins.parser.impl.RawPluginDescriptor
-import com.intellij.platform.plugins.parser.impl.elements.ContentElement
+import com.intellij.platform.plugins.parser.impl.elements.ContentModuleElement
 import com.intellij.platform.plugins.parser.impl.elements.DependenciesElement
 import com.intellij.platform.plugins.parser.impl.elements.ModuleLoadingRule
 import com.intellij.platform.plugins.testFramework.LoadFromSourceXIncludeLoader
@@ -288,8 +288,6 @@ class PluginModelValidator(
       }
 
       val moduleNameToLoadingRule = pluginInfo.descriptor.contentModules
-        .asSequence()
-        .filterIsInstance<ContentElement.Module>()
         .associateBy({ it.name }, { it.loadingRule })
       checkDependencies(
         dependenciesElements = descriptor.dependencies,
@@ -528,13 +526,12 @@ class PluginModelValidator(
   // 2) no depends + no dependency on plugin in a referenced descriptor = directly injected into plugin (separate classloader is not created
   // during a transition period). In old format: xi:include (e.g. <xi:include href="dockerfile-language.xml"/>).
   private fun checkContent(
-    contentElements: List<ContentElement>,
+    contentElements: List<ContentModuleElement>,
     referencingModuleInfo: ModuleInfo,
     sourceModuleNameToFileInfo: Map<String, ModuleDescriptorFileInfo>,
     moduleNameToInfo: MutableMap<String, ModuleInfo>
   ) {
     for (contentElement in contentElements) {
-      contentElement as ContentElement.Module
       fun registerError(message: String, additionalParams: Map<String, Any?> = emptyMap()) {
         reportError(
           message,

platform/plugins/parser/impl/src/com/intellij/platform/plugins/parser/impl/PluginDescriptorBuilder.kt

@@ -58,8 +58,8 @@ interface PluginDescriptorBuilder {
   fun addExtension(qualifiedExtensionPointName: String, extension: ExtensionElement)
   val extensions: Map<String, List<ExtensionElement>>
 
-  fun addContentModule(contentModule: ContentElement)
-  val contentModules: List<ContentElement>
+  fun addContentModule(contentModule: ContentModuleElement)
+  val contentModules: List<ContentModuleElement>
 
   fun addDependency(dependency: DependenciesElement)
   val dependencies: List<DependenciesElement>

platform/plugins/parser/impl/src/com/intellij/platform/plugins/parser/impl/PluginDescriptorBuilderImpl.kt

@@ -96,14 +96,14 @@ internal class PluginDescriptorBuilderImpl : PluginDescriptorBuilder {
   override val extensions: Map<String, List<ExtensionElement>>
     get() = _extensions ?: Java11Shim.INSTANCE.mapOf()
 
-  private var _contentModules: MutableList<ContentElement>? = null
-  override fun addContentModule(contentModule: ContentElement) {
+  private var _contentModules: MutableList<ContentModuleElement>? = null
+  override fun addContentModule(contentModule: ContentModuleElement) {
     if (_contentModules == null) {
       _contentModules = ArrayList()
     }
     _contentModules!!.add(contentModule)
   }
-  override val contentModules: List<ContentElement>
+  override val contentModules: List<ContentModuleElement>
     get() = _contentModules ?: Java11Shim.INSTANCE.listOf()
 
   private var _dependencies: MutableList<DependenciesElement>? = null

platform/plugins/parser/impl/src/com/intellij/platform/plugins/parser/impl/RawPluginDescriptor.kt

@@ -58,6 +58,6 @@ class RawPluginDescriptor(
    * */
   val extensions: Map<String, List<ExtensionElement>>,
 
-  val contentModules: List<ContentElement>,
+  val contentModules: List<ContentModuleElement>,
   val dependencies: List<DependenciesElement>,
 )

platform/plugins/parser/impl/src/com/intellij/platform/plugins/parser/impl/XmlReader.kt

@@ -670,7 +670,7 @@ private fun readContent(reader: XMLStreamReader2, builder: PluginDescriptorBuild
     val isEndElement = reader.next() == XMLStreamConstants.END_ELEMENT
     if (isEndElement) {
       if (os == null || readContext.elementOsFilter(os)) {
-        builder.addContentModule(ContentElement.Module(name = name, loadingRule = loadingRule, embeddedDescriptorContent = null))
+        builder.addContentModule(ContentModuleElement(name = name, loadingRule = loadingRule, embeddedDescriptorContent = null))
       }
     }
     else {
@@ -679,7 +679,7 @@ private fun readContent(reader: XMLStreamReader2, builder: PluginDescriptorBuild
         val toIndex = fromIndex + reader.textLength
         val length = toIndex - fromIndex
         val descriptorContent = if (length == 0) null else reader.textCharacters.copyOfRange(fromIndex, toIndex)
-        builder.addContentModule(ContentElement.Module(name = name, loadingRule = loadingRule, embeddedDescriptorContent = descriptorContent))
+        builder.addContentModule(ContentModuleElement(name = name, loadingRule = loadingRule, embeddedDescriptorContent = descriptorContent))
       }
 
       var nesting = 1

platform/plugins/parser/impl/src/com/intellij/platform/plugins/parser/impl/elements/ContentElement.kt

@@ -1,14 +0,0 @@
-// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
-package com.intellij.platform.plugins.parser.impl.elements
-
-abstract class ContentElement {
-  class Module(
-    val name: String,
-    val loadingRule: ModuleLoadingRule = ModuleLoadingRule.OPTIONAL,
-    val embeddedDescriptorContent: CharArray? = null,
-  ) : ContentElement() {
-    override fun toString(): String {
-      return "Module(name=$name, loadingRule=$loadingRule)"
-    }
-  }
-}

platform/plugins/parser/impl/src/com/intellij/platform/plugins/parser/impl/elements/ContentModuleElement.kt

@@ -0,0 +1,12 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.platform.plugins.parser.impl.elements
+
+class ContentModuleElement(
+  val name: String,
+  val loadingRule: ModuleLoadingRule = ModuleLoadingRule.OPTIONAL,
+  val embeddedDescriptorContent: CharArray? = null,
+) {
+  override fun toString(): String {
+    return "Module(name=$name, loadingRule=$loadingRule)"
+  }
+}