How can we start or signal a process passing a POJO as parameter when using the BPM Suite 6 REST API?

Issue

• We have a process and wanted to start it using a parameter which is not a text or a number, but a custom POJO which is used in the process. Is there any sample on how can we achieve this?
• The REST API to start/complete a task works fine when we pass objects of integer or String type. But when a complex POJO is passed as a parameter its not working as expected. How can we use HTTP to start a process by passing a complex object?