fix: change comparison between call nodes when looking up call and return nodes.

                // Nodes to be paired up

                GraphNode<?> callNode  = vertexSet().stream()

                        .filter(n -> n instanceof CallNode)

                        .filter(n -> n.getAstNode().equals(call.getCall()))

                        .filter(n -> ASTUtils.equalsWithRange(n.getAstNode(), call.getCall()))

                        .collect(toSingleton());

                GraphNode<?> returnNode = vertexSet().stream()

                        .filter(n -> n instanceof CallNode.Return)

                        .filter(n -> n.getAstNode().equals(call.getCall()))

                        .filter(n -> ASTUtils.equalsWithRange(n.getAstNode(), call.getCall()))

                        .collect(toSingleton());

                GraphNode<?> enterNode = cfgMap.get(callGraph.getEdgeTarget(call).getDeclaration()).getRootNode();

                GraphNode<?> exitNode  = cfgMap.get(callGraph.getEdgeTarget(call).getDeclaration()).getExitNode();