Custom Column with column names that have null registers

Hi Anonymous 

I have pasted the Advanced Editor code below

let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45W8i3SU/DKz8hT0lHKSszTNzICMhyTSzLLUoGM/GysRKwORJ9LIlhVWmoZRF9Aal5KZl4KTKUCij4FiLZiPQXnnMTMIpDG3MQiEiwE6vRNLMoEKUtMKsJpIwLDnOmdWpaJ4j+ELgVkZ6Lqck4sysHjOTQC4TvXskSSvBYLAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Supplier = _t, Date = _t, Status = _t, #"Doc 1" = _t, #"Doc 2" = _t, #"Doc 3" = _t, #"Doc 4" = _t, #"Doc 5 " = _t]),
#"Unpivoted Columns" = Table.UnpivotOtherColumns(Source, {"Supplier", "Date", "Status"}, "Attribute", "Value"),
#"Added Conditional Column" = Table.AddColumn(#"Unpivoted Columns", "Document Missing", each if [Value] <> "ok" then [Attribute] else null),
#"Grouped Rows" = Table.Group(#"Added Conditional Column", {"Supplier"}, {{"Grouped Table", each _, type table [Supplier=nullable text, Date=nullable text, Status=nullable text, Attribute=text, Value=text, Custom=nullable text]}}),
#"Added Custom" = Table.AddColumn(#"Grouped Rows", "Documents Missing", each Table.Column([Grouped Table],"Document Missing")),
#"Extracted Values" = Table.TransformColumns(#"Added Custom", {"Documents Missing", each Text.Combine(List.Transform(_, Text.From), ","), type text}),
#"Expanded Grouped Table" = Table.ExpandTableColumn(#"Extracted Values", "Grouped Table", {"Date", "Status", "Attribute", "Value"}, {"Date", "Status", "Attribute", "Value"}),
#"Reordered Columns" = Table.ReorderColumns(#"Expanded Grouped Table",{"Supplier", "Date", "Status", "Documents Missing", "Attribute", "Value"}),
#"Pivoted Column" = Table.Pivot(#"Reordered Columns", List.Distinct(#"Reordered Columns"[Attribute]), "Attribute", "Value"),
#"Replaced Value" = Table.ReplaceValue(#"Pivoted Column","","None",Replacer.ReplaceValue,{"Documents Missing"})
in
#"Replaced Value"

This is what i got

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