Local inspection PsiElement source query

Hi,

I am interested to know whether  

PsiManager.isInProject(psiElement)

is the way to go for finding out whether an element is part of the project files or otherwise part of the project sdk/libraries inside a local inspection?

My inspection is meant to highlight some code smells, but unless the user can do something about it, there's not much point in prioritising it. 

Likewise, for elements that come from libraries, I found that

if (psiElement instanceof PsiCompiledElement) 

is quite a good proxy, but this wouldn't suffice in detecting whether the element is say from the JDK, hence it wouldn't cover all the cases I need.

Best,

Radu