Java implement of braintree payment gateway

We search for a senior expert who is able to create us a implementation of the braintree payment gateway. We are also a developer team but right now we do not have the time to implement the gateway, so we search a senior expert for supporting us. We want to achieve (Requirements): * support for all possible payment methods (paypal, credit & debit card, and so on) * the REST api for a HTML5 client has to be well defined * implementation of these transactions: [login to view URL] Here a good intro into the payment process: [login to view URL] This are samples and also the API code: [login to view URL] [login to view URL] Requirements (technical) As a runtime environment we expect to be runnable on: - in JavaEE 7 (wildfly 10) - Java 8 As the development environment we expect: - Eclipse Neon (no Netbeans, no Idea) - Maven3 Your delivery artefacts are: - eclipse full project(s) incl. configurations and settings (will be provided to you) - the full source code in our repository - we share you a git source repository for delivering the milestones - a fully working [login to view URL] to build the application as a single & runnable jar (provided already) - an proguard obfuscated single and runnable jar (with maven), so no one can easily access the code by reverse engineering (we provide basic and initial setup, but finetunig will be done by you) - your implementation has to confirm to java coding standards and is beside of the functional test one of the acceptance criteria We define following milestones, please name us your delivery dates in the proposal: delivery date for milestone 0 - confirmation of a fully working eclipse development environment - confirmation that git sync with our git is working also fine on your end delivery date for milestone 1 (payment of 10% of the contracted amount) - a UML or a java class level design of the needed classes for the java implementation of the own client REST api, the server classes, the needed model/entity classes) - creation of a test account on your own on braintree which you share with us delivery date for milestone 2 (payment of 40% of the contracted amount) - fully implementation of the initially defined class level design with the braintree test account delivery date for milestone 3 (payment of 15% of the contracted amount) - implemented unit tests to ensure the code is working fine against the braintree test account milestone 4 (payment of 35% of the contracted amount) - after our successful tests and no issues in code reviews findings anymore which we share in the ongoing project. We need for this final payment 2-3 weeks after your last submission of milestone 3