diff --git a/kagglesdk/kaggle_object.py b/kagglesdk/kaggle_object.py
index 6f050e8..cfe4a6a 100644
--- a/kagglesdk/kaggle_object.py
+++ b/kagglesdk/kaggle_object.py
@@ -253,8 +253,8 @@ def set_from_dict(self, instance, json_dict):
         if self.json_name not in json_dict:
             return  # Ignore unknown fields
         value = json_dict[self.json_name]
-        if value == self.default_value:
-            return  # Ignore default values
+        if value is None or value == self.default_value:
+            return  # Ignore null and default values
         try:
             setattr(
                 instance,
diff --git a/kagglesdk/kernels/services/kernels_api_service.py b/kagglesdk/kernels/services/kernels_api_service.py
index 428da2b..b50fd3d 100644
--- a/kagglesdk/kernels/services/kernels_api_service.py
+++ b/kagglesdk/kernels/services/kernels_api_service.py
@@ -22,15 +22,31 @@ def list_kernels(self, request: ApiListKernelsRequest = None) -> ApiListKernelsR
     return self._client.call("kernels.KernelsApiService", "ListKernels", request, ApiListKernelsResponse)
 
   def list_kernel_files(self, request: ApiListKernelFilesRequest = None) -> ApiListKernelFilesResponse:
-    r"""
+    r"""List the source/data files attached to a kernel version.
+
+    Note: this returns files that are part of the kernel's source (scripts,
+    notebooks, attached datasets). To list the output artifacts produced when
+    a kernel runs (CSVs, model weights, predictions, etc.) use
+    list_kernel_session_output instead.
+
     Args:
       request (ApiListKernelFilesRequest):
         The request object; initialized to empty instance if not specified.
+        request.user_name and request.kernel_slug are required.
+
+    Raises:
+      ValueError: if request.user_name or request.kernel_slug is not set.
     """
 
     if request is None:
       request = ApiListKernelFilesRequest()
 
+    if not request.user_name or not request.kernel_slug:
+      raise ValueError(
+        "request.user_name and request.kernel_slug are required. "
+        "If you are trying to list run output files, use list_kernel_session_output instead."
+      )
+
     return self._client.call("kernels.KernelsApiService", "ListKernelFiles", request, ApiListKernelFilesResponse)
 
   def get_kernel(self, request: ApiGetKernelRequest = None) -> ApiGetKernelResponse:
@@ -58,15 +74,30 @@ def save_kernel(self, request: ApiSaveKernelRequest = None) -> ApiSaveKernelResp
     return self._client.call("kernels.KernelsApiService", "SaveKernel", request, ApiSaveKernelResponse)
 
   def list_kernel_session_output(self, request: ApiListKernelSessionOutputRequest = None) -> ApiListKernelSessionOutputResponse:
-    r"""
+    r"""List the output artifacts produced when a kernel runs.
+
+    Use this method to retrieve files generated by a kernel run (CSVs, model
+    weights, predictions, etc.). To list the source/data files that make up
+    the kernel itself, use list_kernel_files instead.
+
     Args:
       request (ApiListKernelSessionOutputRequest):
         The request object; initialized to empty instance if not specified.
+        request.user_name and request.kernel_slug are required.
+
+    Raises:
+      ValueError: if request.user_name or request.kernel_slug is not set.
     """
 
     if request is None:
       request = ApiListKernelSessionOutputRequest()
 
+    if not request.user_name or not request.kernel_slug:
+      raise ValueError(
+        "request.user_name and request.kernel_slug are required. "
+        "If you are trying to list kernel source files, use list_kernel_files instead."
+      )
+
     return self._client.call("kernels.KernelsApiService", "ListKernelSessionOutput", request, ApiListKernelSessionOutputResponse)
 
   def get_kernel_session_status(self, request: ApiGetKernelSessionStatusRequest = None) -> ApiGetKernelSessionStatusResponse:
diff --git a/kagglesdk/kernels/types/kernels_api_service.py b/kagglesdk/kernels/types/kernels_api_service.py
index b01a8ec..b996afb 100644
--- a/kagglesdk/kernels/types/kernels_api_service.py
+++ b/kagglesdk/kernels/types/kernels_api_service.py
@@ -1393,10 +1393,16 @@ def creation_date(self, creation_date: str):
 
 
 class ApiListKernelFilesRequest(KaggleObject):
-  r"""
+  r"""Request to list source/data files attached to a kernel version.
+
+  Use this to enumerate the files that are part of the kernel's source
+  (scripts, notebooks, attached datasets). To list the output artifacts
+  produced when a kernel runs (CSVs, model weights, predictions, etc.),
+  use ApiListKernelSessionOutputRequest with list_kernel_session_output.
+
   Attributes:
-    user_name (str)
-    kernel_slug (str)
+    user_name (str): Required. The owner's username.
+    kernel_slug (str): Required. The kernel slug.
     page_size (int)
     page_token (str)
     version_label (str)
@@ -1526,10 +1532,15 @@ def nextPageToken(self):
 
 
 class ApiListKernelSessionOutputRequest(KaggleObject):
-  r"""
+  r"""Request to list output artifacts produced when a kernel runs.
+
+  Use this to retrieve files generated by a kernel run (CSVs, model weights,
+  predictions, etc.). To list the source/data files that make up the kernel
+  itself, use ApiListKernelFilesRequest with list_kernel_files.
+
   Attributes:
-    user_name (str)
-    kernel_slug (str)
+    user_name (str): Required. The owner's username.
+    kernel_slug (str): Required. The kernel slug.
     page_size (int)
     page_token (str)
     version_label (str)