From the website:
The Java Universal Network/Graph Framework is a software library that provides a common and extensible language for the modeling, analysis, and visualization of data that can be represented as a graph or network. It is written in Java, which allows JUNG-based applications to make use of the extensive built-in capabilities of the Java API, as well as those of other existing third-party Java libraries.
JUNG can be used to process property graphs in Gremlin.
The JUNG team notes that some classes may run into memory issues since JUNG was designed to work with in memory graphs.
Still, it looks like an effective tool for experimenting with exploration and delivery of information as visualized graphs.