'prefix parameter names' checkbox in a material function's settings does nothing.

Prefix Parameter Names checkbox does not work as expected, and the Group names are unmodified.

The value "UMaterialFunction::bPrefixParameterNames" does not appear to be used anywhere in the Engine.

Additional information:
"Prefix Parameter Names" Tooltip text "If true, parameters in this function will have a prefix added to their group name."

1. Download the attached test project and open
2. Open Material “/Game/MF_A” and observe that there is a Parameter named “Param”, with the Group "GroupName"
3. In Material Function Settings observe that "Prefix Parameter Names" is set to "True"
4. Open the Material "/Game/M_Test"
5. Observe that it uses the Material Function "MF_A"
6. Open Material Instance “/Game/MI_Test_Inst”
7. In "Parameter Groups" observe that the Parameter Group "GroupName" is not prefixed with any value.