static struct A {}

@serdeProxy!A
static struct B {}

@serdeProxy!B
static struct C {}

@serdeProxy!B
static struct E {}

static struct D
{
    C c;

    @serdeProxy!E
    int d;
}

import std.meta: AliasSeq;
static assert (is(serdeSerializationFinalProxyMemberTypes!D == AliasSeq!A));