Revert "Revert "quick hack to make filtering callback work with protobufs""

This reverts commit 992e45d69cdf33a6fb0975370700b6ff73ab2aa8.
Revert "Revert "missing interface""

This reverts commit 1da38843e888df35f96478f5a248f5088a16c46f.
null out parser when inflight rpc is removed