8163232: Catalog API: Consolidating CatalogResolver to support all XML ResolversReviewed-by: dfuchs, lancea
8150187: NPE expected if the system identifier is null for CatalogResolverReviewed-by: rriggs, lancea
8077931: Develop tests for XML Catalog APIReviewed-by: joehw, lanceaContributed-by: sha.jiang@oracle.com