Linked Resources: PARENT-N-PROJECT_LOC variable cannot be removed because '-' is rejected on Apply #4351

A project contains a path variable named PARENT-2-PROJECT_LOC.

The variable is visible under:

Project Properties -> Resource -> Linked Resources -> Path Variables

It can be selected and removed in the UI, but when pressing Apply, Eclipse reports:

Path variable name cannot contain character: '-'.

As a result, the variable cannot be removed through the GUI and the only workaround is to manually edit .project.

This is especially problematic because PARENT-2-PROJECT_LOC also has special meaning to the Eclipse path-variable resolver. A stale project variable with this name can shadow the dynamically resolved value.

Example:

PROJECT_LOC = C:\Workspace\CurrentProject\Software\App\IDE_Project

Expected:

PARENT-2-PROJECT_LOC = C:\Workspace\CurrentProject\Software

Actual stale value:

PARENT-2-PROJECT_LOC = C:\Workspace\OldProject\Software

The GUI allows requesting removal of the variable, but applying the change fails because the variable-name validator rejects the - characters.

Expected behavior:
The UI/API should allow deletion of an existing variable even if its name is no longer considered valid, or PARENT-N-* variables should be handled specially so that this invalid state cannot occur.

Workaround:
Manually remove the corresponding variable entry from .project.

Environment:
STM32CubeIDE 1.18.1 / Windows
Eclipse Platform version: [insert version]

Additional note:
Creation/update validation and deletion validation should not necessarily be identical. If an invalid or legacy variable already exists, the UI must still provide a way to remove it.