var google.golang.org/grpc/internal/envconfig.XDSEndpointHashKeyBackwardCompat

one use

	google.golang.org/grpc/internal/envconfig (current package)
		envconfig.go#L60: 	XDSEndpointHashKeyBackwardCompat = boolFromEnv("GRPC_XDS_ENDPOINT_HASH_KEY_BACKWARD_COMPAT", false)