title: TypeError: no implicit conversion of Integer into String
body: <p>In my pipeline this problem occurs: TypeError: no implicit conversion of Integer into String</p>
  
  <p>I am using centos7 and I have installed it by yum</p>
  
  <pre><code># Sample Logstash configuration for creating a simple
  input {
    jdbc {
      jdbc_connection_string =&gt; "jdbc:oracle:thin:@0.0.0.0:1521:DB"
      # The user we wish to execute our statement as
      jdbc_user =&gt; "******"
      jdbc_password =&gt; "*******"
      # The path to our downloaded jdbc driver
      jdbc_driver_library =&gt; "\etc\logstash\conf.d\jdbc\ojdbc7.jar"
      jdbc_driver_class =&gt; "Java::oracle.jdbc.driver.OracleDriver"
      # our query
      statement =&gt; "select * from test"
    }
  }
  output {
    stdout { codec =&gt; json_lines }
    elasticsearch { }
  }
  </code></pre>
  
  <p>It was expected to insert data into elasticsearch</p>