Is Article 7 of Directive 2004/38/EC of the European Parliament and of the Council of 29 April 2004 on the right of citizens of the Union and their family members to move and reside freely within the territory of the Member States (‘the Union Citizens Directive), to be interpreted as meaning that an economically inactive citizen of the European Union may not be a burden on the social assistance system within the meaning of the Union Citizens Directive, if he resides in the host Member State for more than three months, but for less than five years, and derives his right of residence only from his capacity as the spouse (Article 2(2)(a) of the Union Citizens Directive) of a European Union citizen employed in the host Member State (migrant worker) (Article 7(1)(d) of the Union Citizens Directive), but does not himself have an original right of residence under Article 7(1)(a), (b) or (c) of the Union Citizens Directive?