Function polyxml_schema_builder_add_nested_field 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn polyxml_schema_builder_add_nested_field(
    builder: *mut PolyXmlSchemaBuilder,
    name: *const c_char,
    xml_name: *const c_char,
    nested_schema: *const PolyXmlSchema,
    namespace_uri: *const c_char,
)