Java: Add release notes for release 5.18.0 (#2073)

* Add new release notes

* Update release-notes-15-to-29.mdx

---------

Co-authored-by: Alexander Dümont <[email protected]>

Author: bot-sdk-js

docs-java/release-notes/release-notes-15-to-29.mdx

@@ -1,3 +1,16 @@
+## 5.18.0 - April 16, 2025
+
+[All Release Changes](https://github.com/SAP/cloud-sdk-java/releases/tag/rel%2F5.18.0)
+
+### 🔧 Compatibility Notes
+
+- Changed a behavior details when obtaining tokens from IAS with the default strategy `CURRENT_TENANT`.
+  In case the current tenant is the provider tenant, and `TenantAccessor.getCurrentTenant()` is returning a `Tenant` object, this object is now required to have a subdomain != null.
+
+### 🐛 Fixed Issues
+
+- OpenAPI: When `apiMaturity` is set to `beta`, generated enums will now be `@Beta` annotated.
+
 ## 5.17.0 - February 20, 2025
 
 [All Release Changes](https://github.com/SAP/cloud-sdk-java/releases/tag/rel%2F5.17.0)