
replace code 
```java
  ExtensionLoader<T> loader = (ExtensionLoader<T>) EXTENSION_LOADERS.get(type);
    if (loader == null) {
        EXTENSION_LOADERS.putIfAbsent(type, new ExtensionLoader<T>(type));
        loader = (ExtensionLoader<T>) EXTENSION_LOADERS.get(type);
    }
  return loader;
```

to

```java
return (ExtensionLoader<T>) EXTENSION_LOADERS.computeIfAbsent(type, k -> new ExtensionLoader<T>(type));
```


import org.apache.dubbo.common.context.Lifecycle;
import org.apache.dubbo.common.extension.support.ActivateComparator;
import org.apache.dubbo.common.lang.Prioritized;
import org.apache.dubbo.common.logger.Logger;
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.common.utils.ArrayUtils;
import org.apache.dubbo.common.utils.ClassUtils;
import org.apache.dubbo.common.utils.CollectionUtils;
import org.apache.dubbo.common.utils.ConcurrentHashSet;
import org.apache.dubbo.common.utils.ConfigUtils;
import org.apache.dubbo.common.utils.Holder;
import org.apache.dubbo.common.utils.ReflectUtils;
import org.apache.dubbo.common.utils.StringUtils;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;