us-docker.pkg.dev/grpc-testing/testing-images-public/cxx_clang_6_x64:78958e51f94dfb5c8c5e0a1fde2cfa4ccf0fee02@sha256:c5cec74947c06174b21188eb9565f322a8543cd4878dc40b34cfcaee9a5fd94a