[SKIP CI] Add multi-source build steps to PR check workflow

.github/workflows/build_pull_request.yml

@@ -35,6 +35,22 @@ jobs:
           mkdir -p ~/.gradle
           cp .github/runner-files/ci-gradle.properties ~/.gradle/gradle.properties
 
+      - name: Build multi-source library
+        uses: eskatos/gradle-command-action@v1
+        with:
+          arguments: :multisrc:assembleDebug
+          wrapper-cache-enabled: true
+          dependencies-cache-enabled: true
+          configuration-cache-enabled: true
+
+      - name: Run multi-source generators
+        uses: eskatos/gradle-command-action@v1
+        with:
+          arguments: :multisrc:runAllGenerators
+          wrapper-cache-enabled: true
+          dependencies-cache-enabled: true
+          configuration-cache-enabled: true
+
       - name: Build extensions
         uses: eskatos/gradle-command-action@v1
         with: