plugin_extensions.md: cleanup

topics/basics/plugin_structure/plugin_extensions.md

@@ -12,7 +12,7 @@ The following are some of the most common tasks accomplished using extensions:
 * The `com.intellij.applicationConfigurable` and `com.intellij.projectConfigurable` extension points allow plugins to add pages to the [Settings dialog](settings.md);
 * [Custom language plugins](custom_language_support.md) use many extension points to extend various language support features in the IDE.
 
-There are more than 1000 extension points available in the platform and the bundled plugins, allowing customizing different parts of the IDE behavior.
+There are more than 1500 extension points available in the platform and the bundled plugins, allowing customizing different parts of the IDE behavior.
 
 ## Exploring Available Extensions
 
@@ -76,23 +76,27 @@ and one extension to access the `another.plugin.myExtensionPoint` extension poin
 
 Please note the following important points:
 
-- Extension implementations should be stateless. Use explicit [](plugin_services.md) for managing (runtime) data.
+- Extension implementations must be stateless. Use explicit [](plugin_services.md) for managing (runtime) data.
 - Avoid any initialization in constructor, see also notes for [Services](plugin_services.md#constructor).
 
-When using Kotlin:
+When using [Kotlin](using_kotlin.md):
+
 - Do not use `object` but `class` for implementation. [More details](using_kotlin.md#object-vs-class)
 - Do not use `companion object` to avoid excessive classloading/initialization when the extension class is loaded.
-Use top-level declarations or objects instead. [More details](using_kotlin.md#companion-object-extensions)
+  Use top-level declarations or objects instead. [More details](using_kotlin.md#companion-object-extensions)
 
 </procedure>
 
 ### Extension Default Properties
 
-The following properties are available always:
+`id`
+: Unique ID. Consider prepending ID with the prefix related to the plugin name or ID to not clash with other plugins defining extensions with the same ID, e.g., `com.example.myplugin.myExtension`.
 
-* `id` - unique ID. Consider prepending ID with the prefix related to the plugin name or ID to not clash with other plugins defining extensions with the same ID, e.g., `com.example.myplugin.myExtension`.
-* `order` - allows ordering all defined extensions using `first`, `last` or `before|after [id]` respectively
-* `os` - allows restricting an extension to given OS, e.g., `os="windows"` registers the extension on Windows only
+`order`
+: Allows ordering all defined extensions using `first`, `last` or `before|after [id]` respectively.
+
+`os`
+: Allows restricting an extension to given OS, e.g., `os="windows"` registers the extension on Windows only
 
 If an extension instance needs to "opt out" in certain scenarios, it can throw [`ExtensionNotApplicableException`](%gh-ic%/platform/extensions/src/com/intellij/openapi/extensions/ExtensionNotApplicableException.java) in its constructor.
 
@@ -104,6 +108,7 @@ Properties annotated with [`RequiredElement`](%gh-ic%/platform/core-api/src/com/
 If the given property is allowed to have an explicit empty value, set `allowEmpty` to `true` (2020.3 and later).
 
 Property names matching the following list will resolve to fully qualified class name:
+
 - `implementation`
 - `className`
 - `serviceInterface` / `serviceImplementation`
@@ -112,6 +117,7 @@ Property names matching the following list will resolve to fully qualified class
 A required parent type can be specified in the extension point declaration via nested [`<with>`](plugin_configuration_file.md#idea-plugin__extensionPoints__extensionPoint__with):
 
 ```xml
+
 <extensionPoint name="myExtension" beanClass="MyExtensionBean">
   <with
       attribute="psiElementClass"