Not update the indices #4406

Both observations are real and neither is a bug

A param node never reads indices

• lookup descends via children[0] — tree.go:528 tree.go:544 tree.go:902
• insertion does the same — tree.go:181-185
• indices only ever gains static children (tree.go:201-203) and the wildcard child is kept last (tree.go:71) so a param node holds one child at most

Tree for /user/:id/name plus /user/:id/age

path="/user/"  indices=""    wildChild=true
  path=":id"   indices=""    nType=param
    path="/"   indices="na"
      path="name"  handlers
      path="age"   handlers

both resolve fine

Registering /user/:id first then /user/:id/name does put / in the param node indices through tree.go:203 and nothing reads that either

On fullPath every node built inside insertChild carries the whole route path yet the value is only ever consumed on a node that has handlers

• tree.go:537-538 tree.go:578 and tree.go:608-609 copy n.fullPath into the returned value
• gin.go:719-721 reads it only when handlers are non nil

Intermediate values are throwaway already since an edge split rewrites them — tree.go:174 — in the dump above that / node ends up with fullPath="/use"