Should correctly load a third-party diagram using registerDiagram

mindmap
  root
    A
    B
    C
    D
    E
    A2
    B2
    C2
    D2
    E2
    child1((Circle))
        grandchild 1
        grandchild 2
    child2(Round rectangle)
        grandchild 3
        grandchild 4
    child3[Square]
        grandchild 5
        ::icon(mdi mdi-fire)
        gc6((grand
child 6))
        ::icon(mdi mdi-fire)
          gc7((grand
grand
child 8))