code: private boolean fastAllPathsReturnCheck(ControlFlowGraph<Node> cfg) {
      for (DiGraphEdge<Node, Branch> s : cfg.getImplicitReturn().getInEdges()) {
        Node n = s.getSource().getValue();
        // NOTE(dimvar): it is possible to change ControlFlowAnalysis.java, so
        // that the calls that always throw are treated in the same way as THROW
        // in the CFG. Then, we would not need to use the coding convention here.
        if (!n.isReturn() && !convention.isFunctionCallThatAlwaysThrows(n)) {
          return false;
        }
      }
      return true;
    }
docs: Fast check to see if all execution paths contain a return statement.
  May spuriously report that a return statement is missing.
  
  @return true if all paths return, converse not necessarily true