maven在尝试访问nexus存储库时得到“未授权” Not authorized , ReasonPhrase:Unauthorized

<servers>
 <server>
      <id>nexus-release</id>          <---THIS MUST MATCH
      <username>USER_NAME</username>
      <password>USER_PASSWD</password>
  </server>
</servers>
<mirrors>
    <mirror>
      <id>nexus-release</id>          <---THIS
      <mirrorOf>*</mirrorOf>
      <url>http://MY_NEXUS_HOST:8081/nexus/content/groups/public</url>
    </mirror>
  </mirrors>