What is the experience of building add-ons? Any pre-requisite skills? How to avoid Pitfall?
This is a good summary of what is needed to build Jira Server plug-ins; but Cloud plug-ins can be done with them entirely different skill set. Most of our Cloud add-ons (apps) are built using Node and Angular.
You need to learn how the platform work and its key components before you think of making any add on
For a step by step guide, you can refer this book
Hi, this book is nice to begin, but like not enough and not accurate
is there something else ?
I put here all I have found usefull here to start working on addons
https://docs.atlassian.com/aui/7.4.0/docs/forms.html
https://docs.atlassian.com/DAC/javadoc/jira/reference/com/atlassian/jira/ComponentManager.html
http://velocity.apache.org/engine/1.7/user-guide.html#velocity-template-language-vtl-an-introduction
Some samples
http://jiradev.com/workflow-validator.html
For groovy script runner
https://mvnrepository.com/artifact/org.codehaus.groovy/groovy-all/2.4.13
http://mrhaki.blogspot.tw/2009/11/groovy-goodness-running-groovy-scripts.html
https://stackoverflow.com/questions/17790198/how-to-run-groovy-script-in-java
https://www.programcreek.com/java-api-examples/groovy.lang.GroovyShell
Feel free to add stuff, I need more information