When you use the multibranch plugin, the workspace directory is defined with this:

<folders>_<job>_<branch_name>-<id>
Example: Folder1_Job1_master-S2HF5SWCWS7FHWDDHORLKDVCDVKY2KDPDA6LX4SHGLPI3ZY3WMYA

If the branch start with a number (for example 1-feature-initialize-project), the workspace directory is created like this:

-feature-initialize-project-4I7PGYR2TIHTPXJVPZ2FTWX7GPCJ2ZF6TLDSU7LQPMWDHP4ELMAQ