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SyntaxEditor: Add XMLFoldingTagger
In ServicePack version which will be release today we are adding CSharpFoldingTagger, VisualBasicFoldingtagger, BracketFoldingTagger, FoldingTaggerBase classes and the current FoldingTagger class is removed. We will try to add the XMLFoldingTagger for R1 2020 as well.
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