private void updateAddButtonState() {
			boolean enabled = false;

			List<String> selectedUserNames = knownUsersPanel.getSelectedUsers();
			for (String user : selectedUserNames) {
				if (!userAccessPanel.isInProjectAccessList(user)) {
					enabled = true;
					break;
				}
			}
			addButton.setEnabled(enabled);
		}
Updates the 'add' button state based on the selections in the known users panel.
Ghidra/Framework/Project/src/main/java/ghidra/framework/main/ProjectAccessPanel.java