@Override
    public Class<?> getProxyClass() {
        if (proxyClass != null) {
            return proxyClass;
        }
        try {
            if (StringUtils.isNotBlank(interfaceId)) {
                this.proxyClass = ClassUtils.forName(interfaceId);
                if (!proxyClass.isInterface()) {
                    if ((getServer() != null) && getServer().size() != 0) {
                        for (int i = 0; i < getServer().size(); i++) {
                            if (!RpcConstants.PROTOCOL_TYPE_TRIPLE.equals(getServer().get(i).getProtocol())) {
                                throw ExceptionUtils.buildRuntime("service.interfaceId",
                                    interfaceId, "interfaceId must set interface class, not implement class");
                            }
                        }
                    }
                }
            } else {
                throw ExceptionUtils.buildRuntime("service.interfaceId",
                    "null", "interfaceId must be not null");
            }
        } catch (SofaRpcRuntimeException e) {
            throw e;
        } catch (Throwable e) {
            throw new SofaRpcRuntimeException(LogCodes.getLog(LogCodes.ERROR_GET_PROXY_CLASS), e);
        }
        return proxyClass;
    }
Gets proxy class.

@return the proxyClass
core/api/src/main/java/com/alipay/sofa/rpc/config/ProviderConfig.java