I need an operator like the inverse of Filter Stopwords (Dictionary) operator

Hi

Thanks for reading my post

I work on my master thesis and I find same my problem here in this link

http://community.rapidminer.com/t5/RapidMiner-Studio/SOLVED-Filter-text-from-a-list-of-word/td-p/21459

He solve the problem by changing the code for filterstopword(dictionary)

I read the document "How to extend rapidminer"

I prepare the envirmonet by downloding Java and Eclipse Java Neon 

I know now how to create my own operator but I don't know how to copy existing operator code and modify it ?

Thank you again