DOCSP-35411 -- Add workaround for 'Mapping Potentially Null Values at Different Object Depths' to Known Issues. (#431)

* DOCSP-35411 -- Add 'Mapping Potentially Null values at Different Object Depths' to Known Issues

* DOCSP-35411 -- Add 'Mapping Potentially Null values at Different Object Depths' to Known Issues

* DOCSP-35411 -- Add 'Mapping Potentially Null values at Different Object Depths' to Known Issues

* DOCSP-35411 -- Add 'Mapping Potentially Null values at Different Object Depths' to Known Issues

* DOCSP-35411 -- Copy review revisions

* DOCSP-35411 -- remove vscode config

* DOCSP-35411 -- remove reference to documents

* DOCSP-35411 -- fix typo

* DOCSP-35411 -- fix typo

* DOCSP-35411 -- tech review revision

Author: jvincent-mongodb

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "esbonio.sphinx.confDir": ""
+}

source/reference.txt

@@ -13,4 +13,5 @@ Reference
    /reference/type-conversion
    /reference/user-authorization
    /reference/system-variables
+   /reference/known-issues
    /supported-operations

source/reference/known-issues.txt

@@ -68,3 +68,25 @@ Given the exact same |sql| query, the |bi-short| does not return
       GROUP BY class;
 
       Empty set (0.00 sec)
+
+
+BI Connector Returns ``NULL`` Values Due to Mapping Error
+----------------------------------------------------------
+
+A known mapping error can occur that causes |bi-short| to return all ``NULL`` 
+values. This error occurs when you query a collection that
+contains an array field that can be ``NULL``, and the same array contains 
+an additional field that can also be ``NULL``. A workaround for this error is to 
+create a view with the ``$match`` filter that only returns documents in which 
+the field ``$type`` is ``array`` with the ``createView`` method.
+
+
+.. example::
+
+   For a collection named ``nextDeparture`` with an array field named 
+   ``response.schedule`` that is sometimes ``NULL``, you can create 
+   the following view:
+
+   .. code-block:: javascript
+
+      db.createView('nonullsched', '"nextDeparture"',  [{'$match': {'response.schedule': {'$type': 'array'}}}])