static RpcResponse ofFailure(Throwable cause) {
        requireNonNull(cause, "cause");
        final CompletableRpcResponse future = new CompletableRpcResponse();
        future.completeExceptionally(cause);
        return future;
    }
Returns a newly created exceptionally complete {@link RpcResponse}.
core/src/main/java/com/linecorp/armeria/common/RpcResponse.java