Grouping option

Hi Shruthi96 

Here is one way, assume it sorts by Start datetime, not elegant...but does the job

use dummy data

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("fc87DoAgEEXRrRhqEubDFLoVQmFFqTFx/1IZ4cWpyMm7xVBK2EMM7bhP7i8nTkLCy7qRgWv8rZnA31qm1cBvffVcx1kI7OYG9nIlsPNRNbBTZwIPp+RpNnCtDw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Task = _t, Group = _t, Start = _t, End = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Task", type text}, {"Group", type text}, {"Start", type datetime}, {"End", type datetime}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "minStart", each if [Index]=0 then 1 
else if [Group]=#"Added Index"[Group]{[Index]-1} then 0
else 1),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "maxEnd", each try if [Group]=#"Added Index"[Group]{[Index]+1} then 0
else 1 otherwise 1),
    StartTable = Table.AddIndexColumn( Table.SelectColumns( Table.SelectRows(#"Added Custom1", each ([minStart] = 1)),{"Group", "Start"}),"Index", 0, 1, Int64.Type),
    EndTable = Table.AddIndexColumn( Table.SelectColumns( Table.SelectRows(#"Added Custom1", each ([maxEnd] = 1)),{"Group", "End"}),"Index", 0, 1, Int64.Type),
    #"Merged Queries" = Table.NestedJoin(StartTable, {"Group", "Index"}, EndTable, {"Group", "Index"}, "EndTable", JoinKind.LeftOuter),
    #"Expanded EndTable" = Table.ExpandTableColumn(#"Merged Queries", "EndTable", {"End"}, {"End"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded EndTable",{"Index"})
in
    #"Removed Columns"