@Override
    public Message processRequest0(final RaftServerService service, final ReadIndexRequest request,
                                   final RpcRequestClosure done) {
        service.handleReadIndexRequest(request, new RpcResponseClosureAdapter<RpcRequests.ReadIndexResponse>() {

            @Override
            public void run(final Status status) {
                if (getResponse() != null) {
                    done.sendResponse(getResponse());
                } else {
                    done.run(status);
                }
            }

        });
        return null;
    }
Handle read index request.

@author boyan (boyan@alibaba-inc.com)
@author jiachun.fjc
jraft-core/src/main/java/com/alipay/sofa/jraft/rpc/impl/core/ReadIndexRequestProcessor.java