Resolution
There are a few options available when starting to create a plugin, we recommend you start with:
The CloudBees CD (CloudBees Flow) Plugin Development Framework (flowpdf in short) provides a combination of Tools, APIs and libraries which can be used to create a flow plugin in 4 steps. Refer to the Development Process section below.
That page links to the:
CloudBees CD (CloudBees Flow) Plugin Developer Guide
That guide has a Tutorial section that walks you through the process:
Plugin Tutorial using the Framework
An alternative option for creating a plugin is the EC-Admin plugin which has a procedure named projectAsCode that will create a plugin from a project.
Depending on your use case, you may be able to use the API instead of writing a plugin, which is documented here:
CloudBees Flow APIs (version 9.1)
The documentation for other versions of the API can be found at:
https://docs.electric-cloud.com/eflow_doc/FlowIndex.html