public default VisualizationViewer<V, E> getViewer(MouseEvent e) {
		GraphViewer<V, E> viewer = getGraphViewer(e);
		return viewer;
	}
An interface to provide a common set of methods for classes that could not otherwise 
extend an abstract class.  This interface signals that the implementer is a {@link VisualGraph}
mouse plugin.

<P>Note: The implementors of this interface still use the deprecated 
{@link MouseEvent#getModifiers()} method, since many of those classes extends from 
3rd-party classes that still use them, such as {@link PickingGraphMousePlugin}.   We will need
to update the library (if/when possible), or rewrite our code so that it does not use the 
old 3rd-party algorithms. 

@param <V> the vertex
@param <E> the edge
Ghidra/Framework/Graph/src/main/java/ghidra/graph/viewer/event/mouse/VisualGraphMousePlugin.java