JHipster app tweak (Java)

Hello. We have a web application based on JHipster (Java) that we need to modify. The software is a platform that an outsourced company did for us. We have the code so we can modify it. We need to tweak it to include some additional features and some backend processess. Additional details would be provided explaining all the system, how it works, and the exact job to be done. We are looking for someone with experience in Java and in particular JHipster. We will start with a relatively minor modification (assume 5-10 hours of understanding exactly what needs to be done and the code behind and another 5-10 days of coding) but we have more functionalities to include, that we might continue developing if the first result is sucessfull.