com.alibaba.dubbo.governance.web.governance.module.screen.Providers#getServiceAppMap 
at line 133 ， should be providers.size > 0 or just delete this comparison cause the next for will skip if proviers.size == 0
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
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package com.alibaba.dubbo.governance.web.governance.module.screen;
import com.alibaba.dubbo.common.utils.StringUtils;
import com.alibaba.dubbo.governance.service.OverrideService;
import com.alibaba.dubbo.governance.service.ProviderService;
import com.alibaba.dubbo.governance.web.common.module.screen.Restful;
import com.alibaba.dubbo.registry.common.domain.Override;
import com.alibaba.dubbo.registry.common.domain.Provider;
import com.alibaba.dubbo.registry.common.route.OverrideUtils;
import com.alibaba.dubbo.registry.common.util.Tool;