I don't know if this is a bug or by design, but I find it very annoying that when I try to use the geoprocessing tool Export XML Workspace Document in ArcGIS Pro 2.3 and browse to a file path with a .xml extension that it automatically adds .z to the end of it when it returns to the geoprocessing tab. I don't want to have to unzip it immediately nor do I want it to change what I typed in. Using a zip archive should be optional. It is noted in the documentation. I can override it from the input parameters tab, but I found this very annoying.
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