As of the 29th August 2019, the Hyperledger Composer project is in deprecated status. None of the maintainers are actively developing new features. None of the maintainers are actively providing support via GitHub issues. However, if you wish to submit code changes via pull requests, these will be merged.
It is highly recommended that you use Hyperledger Fabric v1.4+ instead, which features significant improvements to the developer experience, including a new programming model.
More information available here: What’s new in Hyperledger Fabric v1.4
Hyperledger Composer is a set of collaboration tools for building blockchain business networks that make it simple and fast for business owners and developers to create smart contracts and blockchain applications to solve business problems.