When I customize the udf function plugin，met a problem,java.lang.IllegalStateException: No service providers of type io.prestosql.spi.Plugin

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When I customize the udf function plugin，met a problem

java.lang.IllegalStateException: No service providers of type io.prestosql.spi.Plugin

trino version is 350

import com.google.common.collect.ImmutableSet;
import io.prestosql.spi.Plugin;

import java.util.Set;

//Presto 注册自定义函数的类，此类需要继承Plugin接口
public class MyFunctionsPlugin implements Plugin {
@OverRide
public Set<Class> getFunctions() { return ImmutableSet.>builder()
.add(MyUDF.class)
.build();
}
}

public class MyUDF {
@ScalarFunction("lower_cxk")

@Description("hive to_date function")

@SqlType(StandardTypes.VARCHAR)

public static Slice lower_cxk(@SqlType(StandardTypes.VARCHAR) Slice input) {

    String argument = input.toStringUtf8();

    return Slices.utf8Slice(argument.toLowerCase());

}

}

META-INF.service/io.prestosql.spi.Plugin
org.example.xx.MyFunctionsPlugin

How to troubleshoot this problem?