Why has javassist never had a method as useful as this?

The purpose of this method is to make changes to code where the line number or variable name is unknown or does not exist. I use it for some obfuscated code, but it doesn't work for all obfuscated code. For unobfuscated code it obviously works.
The implementation is included with a test.
This is the only method that got the expected result as JVM is not my area of expertise.
I hope I've helped. Thank you very much and have a nice day!