Build and Modify Bonita Community edition

Hello , We need a Java developer familiar with Bonita soft community edition [login to view URL] , We need to download , build and modify source code of community edition ([login to view URL]) to do the following : 1- develop new "Custom Human Task" that can display external web application page (instead of bonita forms ) , this task must accept a url defined in process designer and it should pass some parameters in the url. 2- We will provide the necessary online environment(developer must list the required requirements ) 3- we can extend this project to include other features after agreement on extra fees (if exists) .