What is the meaning of usedBy=0?

[perzonaljezus]

The components report shows entries with usedBy = 0.
I assume it means that the component isn't in the portfolio codebase.
E.g. in the screenshot FastInfoset version 1.2.13 is not in the code base (usedBy=0), but 1.2.16 is (usedBy=2).

But what is the meaning of the entry FastInfoset 1.2.13?
Why is this reported, since FastInfoset 1.2.13 is not in the codebase?

I am using Dependency-Track v3.8.0.

[nscuro]

Dependency-Track < 4.0.0 did not remove unreferenced components from the portfolio. You're seeing FastInfoset 1.2.13, because it was at some point a dependency of one of your projects. You will not see this behavior in DT 4.0.0 and above.