@Override
    public void setAttributes(Map<String, String> attributes) {

        // Create independent, mutable copy of attributes
        attributes = new HashMap<>(attributes);

        // Loop through extension-specific attributes, only sending ones
        // that are non-null and non-empty to the underlying storage mechanism.
        for (String attribute : RESTRICT_CONNECTIONGROUP_ATTRIBUTES) {
            String value = attributes.get(attribute);
            if (value != null && value.isEmpty())
                attributes.put(attribute, null);
        }

        super.setAttributes(attributes);

    }
Returns the original ConnectionGroup object wrapped by this
RestrictConnectionGroup.

@return
    The wrapped ConnectionGroup object.
extensions/guacamole-auth-restrict/src/main/java/org/apache/guacamole/auth/restrict/connectiongroup/RestrictedConnectionGroup.java