what is JGraphModelAdapter in jgrapht library? why we need to it?

JGraphModelAdapter m_jgAdapter;
ListenableGraph g = new ListenableDirectedGraph( DefaultEdge.class );
 
// create a visualization using JGraph, via an adapter
m_jgAdapter = new JGraphModelAdapter( g );
 
JGraph jgraph = new JGraph( m_jgAdapter );
 
adjustDisplaySettings( jgraph );
getContentPane(  ).add( jgraph );
resize( DEFAULT_SIZE );
 
// add some sample data (graph manipulated via JGraphT)
g.addVertex( "v1" );
g.addVertex( "v2" );
g.addVertex( "v3" );