update changelogs

Author: tstanmay13

fern/products/sdks/overview/java/changelog/2025-09-16.mdx

@@ -0,0 +1,7 @@
+## 3.4.1
+**`(fix):`** Fix compilation errors when undiscriminated unions contain multiple members that resolve
+to the same Java type (e.g., multiple strings, string vs string enum). The generator now
+correctly disambiguates duplicate method signatures by adding numeric suffixes (of2, of3,
+visit2, visit3) to factory and visitor methods when needed.
+
+