title: Elasticsearch "StatusLogger Log4j2 could not find a logging implementation. Please add log4j-core to the classpath."
body: <p>I upgraded elasticsearch java client from 2.3 to 5.1.</p>
  
  <p>And this error log continues to appear.</p>
  
  <pre><code>ERROR StatusLogger Log4j2 could not find a logging implementation. Please add log4j-core to the classpath. Using SimpleLogger to log to the console...
  </code></pre>
  
  <p>I'm using log4j2</p>
  
  <pre><code>&lt;dependency&gt;
      &lt;groupId&gt;org.apache.logging.log4j&lt;/groupId&gt;
      &lt;artifactId&gt;log4j-api&lt;/artifactId&gt;
      &lt;version&gt;2.7&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;org.apache.logging.log4j&lt;/groupId&gt;
      &lt;artifactId&gt;log4j-core&lt;/artifactId&gt;
      &lt;version&gt;2.7&lt;/version&gt;
  &lt;/dependency&gt;
  </code></pre>