Added documentation for adding extensions

docs/README.adoc

@@ -2,6 +2,12 @@
 
 Documentation is built using the `mkdocs` tool.
 See link:https://www.mkdocs.org/user-guide/installation/[Installation guide] on how to install it.
+On top of that install these 3 plugins:
+```
+pip install mkdocs-material
+pip install mkdocs-build-plantuml-plugin
+pip install mkdocs-macros-plugin
+```
 Then, building the documentation locally will be as simple as running `mkdocs build` in the root
 of this repository (NOT in the `docs` directory) - the output should appear in the `site` directory.
 To fix a few things, like making links work correctly, you should serve the site

docs/extensions.md

@@ -0,0 +1,44 @@
+# Adding extensions to GraphQL response
+**SmallRye GraphQL** allows the user to add their own extensions inside the GraphQL response
+which is received from the server. The `extensions` are stored next to the `data` field in the GraphQL response.
+
+``` json
+{
+  "data": {
+    "shirt": {
+      "size": "L"
+    }
+  },
+  "extensions": {
+    "country": "Germany",
+    "pi": 3.1415926535
+  }
+}
+```
+
+To add extensions, you need to `@Inject` an instance of `SmallRyeContext` in your `@GraphQLApi` annotated class.
+After that, you can add your own extensions via the method `addExtensions`
+with its input parameters: `key : String` as an identification of the added extension.
+And `value: Object` as a value of the extension. Value can be any given object that can be converted into JsonValue.
+
+As an example, this class below contains the query `getShirt` and during the http request, the query adds these extensions:
+`{"country": "Germany", "pi": 3.1415926535}`.
+These extensions will be sent back via response in the `extensions` field.
+```java
+import jakarta.inject.Inject;
+
+@GraphQLApi
+public class ShirtResources {
+    @Inject
+    SmallRyeContext smallRyeContext;
+
+    @Query
+    public Shirt getShirt() {
+        smallRyeContext.addExtensions("country", "Germany");
+        smallRyeContext.addExtensions("pi", 3.1415926535);
+        //...
+    }
+}
+```
+> [NOTE]
+> You can also use the method `setAddedExtensions(Map<String, Object> addedExtensions)` to set all the extensions with map instance.

mkdocs.yml

@@ -9,6 +9,7 @@ nav:
       - Directives: 'directives.md'
       - Federation: 'federation.md'
       - Custom error extensions: 'custom-error-extensions.md'
+      - Response extensions: 'extensions.md'
   - Typesafe client:
       - Basic usage: 'typesafe-client-usage.md'
       - Reactive: 'typesafe-client-reactive-types.md'

server/implementation/src/main/java/io/smallrye/graphql/execution/context/SmallRyeContext.java

@@ -49,10 +49,21 @@ public Map<String, Object> getAddedExtensions() {
         return addedExtensions;
     }
 
+    /**
+     * Sets the entire map of extension(s) into the context.
+     * 
+     * @param addedExtensions The Map object containing extension(s).
+     */
     public void setAddedExtensions(Map<String, Object> addedExtensions) {
         this.addedExtensions = addedExtensions;
     }
 
+    /**
+     * Adds single instance of user created extension into the context.
+     * 
+     * @param key The key (identification) of the extension.
+     * @param value The value of extension.
+     */
     public void addExtension(String key, Object value) {
         addedExtensions.put(key, value);
     }