Thanks for your query.
Data validations (including drop downs or list type) were also supported in older versions (including aspose-cells-7.3.5.jar), see the document with example code for your reference:
Please note the example code is provided using newer/latest version of the product (Aspose.Cells
for Java v19.8). You may refer to the sample and write your code accordingly and it is also possible that you might need to update your code segment a bit.
PS. We also recommend you to kindly upgrade to and try our latest version of the product which has more enhancements and other fixes.