TDT-2790 Clarify event visibility default is Google-only (#333)

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

Author: samLRodrigues

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Nylas Java SDK Changelog
 
+## [Unreleased]
+
+### Changed
+* Clarify that event `default` visibility is Google-only
+
 ## [v2.17.1] - Release 2026-06-25
 
 ### Fixed

src/main/kotlin/com/nylas/models/EventVisibility.kt

@@ -4,6 +4,10 @@ import com.squareup.moshi.Json
 
 /**
  * Enum representation of visibility of the event, if the event is private or public.
+ *
+ * [DEFAULT] is only valid for Google events, where it defers to the calendar's own sharing
+ * settings. Microsoft and EWS events only support [PUBLIC] and [PRIVATE]; sending `default`
+ * for these providers returns a 400 error.
  */
 enum class EventVisibility {
   @Json(name = "default")