Hi Florian,
Please try the below code
lo_nd_project->set_attribute_property(
EXPORTING
attribute_name = 'PROJECT_NO' " Attribute Name
property = 3 " Read Only property
value = abap_true
index = USE_LEAD_SELECTION " Element Index
all_elements = ABAP_TRUE " Set Properties for All Elements
).
Hope this helps you.
Regards,
Rama