Match directory descriptors with absolute path to existing ones with relative paths

[SebastianWendorf]

I have a scanned directory (container has absolute path, all sub-directories and files relative paths).
I want to scan some sub-directory of the already scanned one by providing its absolute path.
I expect that the existing file-sub-tree is replaced by a newly scanned one where the provided sub-directory serves a container and has an absolute path and all of its sub-directories and files have a path that is relative to the newly scanned sub-directory.

Example:
After initial scan of root directory:

/home/.../project
|- /some-config.json
| /src
| | /src/MyClass.java
| /subproject 
| | /subproject/some-other-config.json
| | /subproject/src
| | | /subproject/src/SomeSubprojectClass.java

After "rescanning" sub-directory:

/home/.../project
| /some-config.json
| /src
| | /src/MyClass.java
| /home/.../project/subproject     -> newly scanned subdirectory
| | /some-other-config.json
| | /src
| | | /src/SomeSubprojectClass.java