newMaybe
Depending on if @child is null, either wraps @child inside of a maybe container or creates a Nothing instance for the given @type.
At least one of @child_type and @child must be non-null. If @child_type is non-null then it must be a definite type. If they are both non-null then @child_type must be the type of @child.
If @child is a floating reference (see g_variant_ref_sink()), the new instance takes ownership of @child.
Return
a floating reference to a new #GVariant maybe instance
Since
2.24
Parameters
childType
the #GVariantType of the child, or null
child
the child value, or null