Why Defects4J was not used?

[ramsey-coding]

Just curious to know why Defects4J was not used in the evaluation which is more popular and widely used?

[mechtaev]

BugsInPy is very similar to Defects4J, but in Python. Python is currently the most popular language according to TIOBE (https://www.tiobe.com/tiobe-index/), and due to its dynamic nature, its has unique bugs that are worth studying.