Java application that provides a service for indexing text files. The console interface should allow for (i) specifying the indexed files and directories and (ii) querying files containing a given word. The library should be extensible by the tokenization algorithm (simple splitting by words/support lexers/etc.). State persistence between running sessions is not needed, but the application should be able to serve consecutive requests. Providing some tests and usage examples is advised. Usage of external libraries is discouraged.