update changelogs

Author: dsinghvi

fern/products/sdks/generators/java/changelog/2026-04-24.mdx

@@ -0,0 +1,9 @@
+## 4.5.0
+**`(feat):`** Support omitting username or password from basic auth when configured via
+`usernameOmit`/`passwordOmit` in the IR. When a field is omitted, it is
+removed from the SDK's public API (`credentials()` takes fewer arguments)
+and an empty string is used internally for the auth header encoding. When
+both fields are omitted, the `credentials()` call and Authorization header
+are skipped entirely.
+
+