Class API/User

@Override
    public DataMutateResult setPrimaryGroup(@Nonnull String group) {
        Objects.requireNonNull(group, "group");
        if (getPrimaryGroup().equalsIgnoreCase(group)) {
            return DataMutateResult.ALREADY_HAS;
        }

        if (!this.handle.hasPermission(NodeFactory.buildGroupNode(group.toLowerCase()).build()).asBoolean()) {
            return DataMutateResult.FAIL;
        }

        this.handle.getPrimaryGroup().setStoredValue(group.toLowerCase());
        return DataMutateResult.SUCCESS;
}