@Deprecated
    protected final O execute(SessionProtocol protocol, EndpointGroup endpointGroup, HttpMethod method,
                              RequestTarget reqTarget, I req) {
        return execute(protocol, endpointGroup, method, reqTarget, req, RequestOptions.of());
    }
Executes the specified {@link Request} via the delegate.

@param protocol the {@link SessionProtocol} to use
@param endpointGroup the {@link EndpointGroup} of the {@link Request}
@param method the method of the {@link Request}
@param reqTarget the {@link RequestTarget} of the {@link Request}
@param req the {@link Request}

@deprecated prefer {@link ClientOptions#clientPreprocessors()} to execute requests
core/src/main/java/com/linecorp/armeria/client/UserClient.java