diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
index 79a7e0e..c9eca43 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
@@ -141,8 +141,12 @@
      * implementations are provided in the stub for OEM to construct the
      * {@link Camera2OutputConfigImpl} and {@link Camera2SessionConfigImpl} instances.
      *
-     * @param previewSurfaceConfig       output surface for preview
-     * @param imageCaptureSurfaceConfig  output surface for image capture.
+     * @param previewSurfaceConfig       output surface for preview, which may contain a
+     *                                   <code>null</code> surface if the app doesn't specify the
+     *                                   preview surface.
+     * @param imageCaptureSurfaceConfig  output surface for still capture, which may contain a
+     *                                   <code>null</code> surface if the app doesn't specify the
+     *                                   still capture surface.
      * @param imageAnalysisSurfaceConfig an optional output config for image analysis
      *                                   (YUV_420_888).
      * @return a {@link Camera2SessionConfigImpl} consisting of a list of
diff --git a/camera2/extensions/service_based_sample/oem_library/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java b/camera2/extensions/service_based_sample/oem_library/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
index fabfc2b..f470a55 100644
--- a/camera2/extensions/service_based_sample/oem_library/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
+++ b/camera2/extensions/service_based_sample/oem_library/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
@@ -89,8 +89,12 @@
      * implementations are provided in the stub for OEM to construct the
      * {@link Camera2OutputConfigImpl} and {@link Camera2SessionConfigImpl} instances.
      *
-     * @param previewSurfaceConfig       output surface for preview
-     * @param imageCaptureSurfaceConfig  output surface for image capture.
+     * @param previewSurfaceConfig       output surface for preview, which may contain a
+     *                                   <code>null</code> surface if the app doesn't specify the
+     *                                   preview surface.
+     * @param imageCaptureSurfaceConfig  output surface for still capture, which may contain a
+     *                                   <code>null</code> surface if the app doesn't specify the
+     *                                   still capture surface.
      * @param imageAnalysisSurfaceConfig an optional output config for image analysis
      *                                   (YUV_420_888).
      * @return a {@link Camera2SessionConfigImpl} consisting of a list of
diff --git a/camera2/extensions/stub/src/main/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java b/camera2/extensions/stub/src/main/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
index 253f021..57fffd0 100644
--- a/camera2/extensions/stub/src/main/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
+++ b/camera2/extensions/stub/src/main/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
@@ -141,8 +141,12 @@
      * implementations are provided in the stub for OEM to construct the
      * {@link Camera2OutputConfigImpl} and {@link Camera2SessionConfigImpl} instances.
      *
-     * @param previewSurfaceConfig       output surface for preview
-     * @param imageCaptureSurfaceConfig  output surface for image capture.
+     * @param previewSurfaceConfig       output surface for preview, which may contain a
+     *                                   <code>null</code> surface if the app doesn't specify the
+     *                                   preview surface.
+     * @param imageCaptureSurfaceConfig  output surface for still capture, which may contain a
+     *                                   <code>null</code> surface if the app doesn't specify the
+     *                                   still capture surface.
      * @param imageAnalysisSurfaceConfig an optional output config for image analysis
      *                                   (YUV_420_888).
      * @return a {@link Camera2SessionConfigImpl} consisting of a list of