where is the importer sourcecode

I want to develop the Importer Data module,but i can't find where is the sourcecode.At present,
What I am seeing is the compiled js file located in the package directory.Thank you very much.

The issue mentions only the Importer Data module and a compiled JavaScript file in the package directory. Start by searching the repository for the Importer Data module and tracing the package build inputs; done means documenting where its source code lives.

Written by the indexing model from the issue text.