Update meta validation to allow lists of strings

Author: nocoding03

pandas/io/json/_normalize.py

@@ -269,7 +269,7 @@ def _simple_json_normalize(
 
 def _validate_meta(meta: list) -> None:
     """
-    Validate that meta parameter contains only strings.
+    Validate that meta parameter contains only strings or lists of strings.
 
     Parameters
     ----------
@@ -279,12 +279,19 @@ def _validate_meta(meta: list) -> None:
     Raises
     ------
     TypeError
-        If meta contains non-string elements.
+        If meta contains elements that are not strings or lists of strings.
     """
     for item in meta:
-        if not isinstance(item, str):
+        if isinstance(item, list):
+            for subitem in item:
+                if not isinstance(subitem, str):
+                    raise TypeError(
+                        "All elements in nested meta paths must be strings. "
+                        f"Found {type(subitem).__name__}: {subitem!r}"
+                    )
+        elif not isinstance(item, str):
             raise TypeError(
-                "All elements in 'meta' must be strings. "
+                "All elements in 'meta' must be strings or lists of strings. "
                 f"Found {type(item).__name__}: {item!r}"
             )