code: private function getAmbiguityExceptionMessage(array $paths, Vertex $startVertex, Vertex $endVertex)
      {
          $textPaths = [];
          $i = 1;
          foreach ($paths as $path) {
              $textPaths[] = 'Path '.$i.': '.$this->getTextualPath($path, $startVertex);
              ++$i;
          }
  
          $msg = sprintf("There are many possible shortest paths between table '%s' and table '%s'\n\n",
              $startVertex->getId(), $endVertex->getId());
  
          $msg .= implode("\n\n", $textPaths);
  
          return $msg;
      }
docs: Returns the full exception message when an ambiguity arises.
  
  @param Base[][] $paths
  @param Vertex   $startVertex