Say, I have some java code like
And some arbitrarily named xml file/files with contents like
<action id="bar" attribute1="ok" attribute="lol"/>
I want to write a plugin that enables jumping to an action declaration from my java code, i.e. I click Ctrl+B/Ctrl+Click ("Go to Declaration") when my cursor is inside "foo.bar" string literal and jump right into declaration of action with attribute id="bar" that is located inside actions with id="foo".
What extension points and what approach should I use? Maybe you can point at some code I can get inspiration from.