|  |  |           +-- secondary-reverse-path
    |  |  |              ...
    |  |  |              +-- primary-reverse-path* []
    |  |  |                 +-- (primary-reverse-path-exist)
    |  |  |                    +--:(path-ref)
    |  |  |                    |  +-- primary-path-ref    leafref
    |  |  |                    +--:(path-request-ref)
    |  |  |                       +-- path-request-ref    leafref