Rename additionalPRoperties indexer name in Financials module.

Author: peombwa

src/Financials/Financials/readme.md

@@ -32,6 +32,29 @@ title: $(service-name)
 subject-prefix: ''
 
 ```
+
+### Directives
+
+> see https://github.com/Azure/autorest/blob/master/docs/powershell/directives.md
+
+``` yaml
+directive:
+# Modify generated .dictionary.cs model classes in Financials module.
+  - from: source-file-csharp
+    where: $
+    transform: >
+      if (!$documentPath.match(/generated%5Capi%5CModels%5CMicrosoftGraph\w*\d*.dictionary.cs/gm))
+      {
+        return $;
+      } else {
+        // Rename additionalProperties indexer name in Financials module from Item to EntityItem to avoid property name conflict. salesOrderLine has a property named item.
+        // See https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/indexers/using-indexers
+        let indexerRegex = /(^\s*)(public\s*global::System.Object this\[global::System.String index\]\s*{\W.*}$)/gm
+        $ = $.replace(indexerRegex, '$1[System.Runtime.CompilerServices.IndexerName("EntityItem")]\n$1$2');
+        return $;
+      }
+```
+
 ### Versioning
 
 ``` yaml