Update KDoc and changelog entry

Author: andrewheard

firebase-vertexai/CHANGELOG.md

@@ -1,7 +1,12 @@
 # Unreleased
 * [changed] Added new exception type for quota exceeded scenarios.
 * [feature] `CountTokenRequest` now includes `GenerationConfig` from the model.
-* [changed] `ImagenInlineImage.data` is now returned as binary instead of base64. (#6800)
+* [changed] **Breaking Change**: `ImagenInlineImage.data` now returns the raw
+  image bytes (in JPEG or PNG format, specified in `ImagenInlineImage.mimeType`)
+  instead of Base64-encoded data. (#6800)
+    * **Action Required:** Remove any Base64 decoding from your
+      `ImagenInlineImage.data` usage.
+    * The `asBitmap()` helper method is unaffected and requires no code changes.
 
 # 16.2.0
 * [fixed] Added support for new values sent by the server for `FinishReason` and `BlockReason`.

firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/type/ImagenInlineImage.kt

@@ -20,10 +20,11 @@ import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 
 /**
- * Represents an Imagen-generated image that is contained inline
+ * Represents an Imagen-generated image that is returned as inline data.
  *
- * @param data Contains the raw bytes of the image
- * @param mimeType Contains the MIME type of the image (for example, `"image/png"`)
+ * @property data The raw image bytes in JPEG or PNG format, as specified by [mimeType].
+ * @property mimeType The IANA standard MIME type of the image data; either `"image/png"` or
+ * `"image/jpeg"`; to request a different format, see [ImagenGenerationConfig.imageFormat].
  */
 @PublicPreviewAPI
 public class ImagenInlineImage