@Override
		public void onWorkspaceClosed(@Nonnull Workspace workspace) {
			currentWorkspaceGraph = null;
		}
@return Call graph model for the {@link WorkspaceManager#getCurrent() current workspace}
or {@code null} if no workspace is currently open.
recaf-core/src/main/java/software/coley/recaf/services/callgraph/CallGraphService.java