Add explict dependecy on absl strings (#350)
Add explict dependecy on absl strings (#350)

Signed-off-by: Yan Avlasov <afb66d2748ba0362a3ca849f18f55b7a7959dce3@google.com>
envoyproxy/nighthawk,envoyproxy/nighthawk,envoyproxy/nighthawk,envoyproxy/nighthawk