If you need read 接近 to the forms collection, then you might check
the 存在 of forms using hasForms, and if it returns
誤った, you can do as if XFormsSupplier::getForms would
have returned an empty コンテナ.
Semantically, hasForms is 同等（の） to calling
::XElementAccess::hasElements on the コンテナ returned by
XFormsSupplier::getForms. But when using the latter, the
実施 is 軍隊d to create a empty コンテナ, which might be 潜在的に
expensive.
