public void setRequiredPermissions(final DocumentPermission... requiredPermissions) {
        this.requiredPermissions = NullSafe.asSet(requiredPermissions);
        explorerPopupPresenter.setRequiredPermissions(requiredPermissions);

        // In case this is called after setSelectedEntityReference, call that again to
        // do the perm check now that we know what perms are needed.
        if (value != null) {
            setSelectedEntityReference(value, true, null, null);
        }
    }
Call this if the selection box contains more than one {@link DocRef} type,
e.g. all data source types. Value should be singular and in
sentence case, e.g. 'Data Source'.

@param itemType
stroom-core-client/src/main/java/stroom/explorer/client/presenter/DocSelectionBoxPresenter.java