@@ -54,7 +54,6 @@ public final class VersionRuleUtils {
         return versionRule;
       }
     }
-
-    throw new IllegalStateException("never run to here");
+    throw new IllegalStateException("config service_description.version is invalid ");
   }
 }
/*
 * 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
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 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
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package org.apache.servicecomb.serviceregistry.version;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Objects;

import org.apache.servicecomb.foundation.common.concurrent.ConcurrentHashMapEx;

public final class VersionRuleUtils {
  private static List<VersionRuleParser> parsers = new ArrayList<>();

  private static Map<String, VersionRule> versionRuleCache = new ConcurrentHashMapEx<>();

  static {
    parsers.add(new VersionRuleLatestParser());
    parsers.add(new VersionRuleStartFromParser());
    parsers.add(new VersionRuleRangeParser());
    parsers.add(new VersionRuleFixedParser());
  }

  //1.0
  //1.0.0+
  //1.0.0-2.0.0
  //latest
  public static VersionRule getOrCreate(String strVersionRule) {
    Objects.requireNonNull(strVersionRule);

    return versionRuleCache.computeIfAbsent(strVersionRule, VersionRuleUtils::create);
  }

  public static VersionRule create(String strVersionRule) {
    strVersionRule = strVersionRule.trim();
    for (VersionRuleParser parser : parsers) {
      VersionRule versionRule = parser.parse(strVersionRule);
      if (versionRule != null) {
        return versionRule;
      }
    }

    throw new IllegalStateException("never run to here");
  }
}

why versionRule relate to "service_description.version"?