GFilterInputStream: why "close-base-stream" property marked as "construct-only"?

["Andrew W. Nosenko" <andrew w nosenko gmail com>]

GFilterInputStream documentation (and implementation) clearly states
that "close-base-stream" property is "construct-only".  And
g_object_set() forbids to change it indeed.

But, from another hand, existence of
g_filter_input_stream_set_close_base_stream() and code in
    gio/tests/buffered-input-stream.c
and
    gio/gdbusauth.c
clearly shows that this flag really intended to be changed at
run-time, after construction.

Is there a reason to keep this property to be contruct-only,
preventing g_object_set() from changing it?

-- 
Andrew W. Nosenko <andrew w nosenko gmail com>