The validity checks run are:

geoJSON parsing: Is the geoJSON valid geoJSON? If not a parsing exception will be thrown with an error message.

geoTools, OGC validity of geometries and geographies.

Microsoft SQL Server validity checks for the input shape as a Geometry and as a Geography to verify it will function properly in SQL Server GIS operations.

Additional checks:

Notifies the user of the point rotation method used for any geometries, ESRI or non-ESRI rotation. (If the geometries are invalid, the corrected geometry will be set to be non-ESRI, i.e. OGC compliant, rotations.)