Allow merge keys (#79)

.vscode/launch.json

@@ -59,6 +59,7 @@
             "args": [
                 "--extensionDevelopmentPath=${workspaceFolder}/src/test/clientExtension",
                 "--disable-extension=ms-azuretools.vscode-docker", // Keep the Docker extension from running so it doesn't interfere with testing
+                "--disable-extension=redhat.vscode-yaml", // Keep the YAML extension from running so it doesn't interfere with testing
             ],
             "preLaunchTask": "tsc-watch: client extension",
             "presentation": {

src/service/ComposeDocument.ts

@@ -169,7 +169,7 @@ export class ComposeDocument {
     }
 
     private buildYamlDocument(): YamlDocument {
-        const composedTokens = new Composer().compose(this.fullCst.value, true);
+        const composedTokens = new Composer({ merge: true }).compose(this.fullCst.value, true);
         const [yamlDocument] = composedTokens;
 
         if (!isDocument(yamlDocument)) {