Looks up the value for a property from the cache. This call does no
blocking IO.
If proxy has an expected interface (see
"g-interface-info"), then property_name (for existence)
is checked against it.
Since 2.26
A reference to the GVariant instance that holds the value for property_name or NULL if the value is not in the cache. The returned reference must be freed with g_variant_unref().
Looks up the value for a property from the cache. This call does no blocking IO. If proxy has an expected interface (see "g-interface-info"), then property_name (for existence) is checked against it. Since 2.26