TypeError: no implicit conversion of Integer into String

In my pipeline this problem occurs: TypeError: no implicit conversion of Integer into String

I am using centos7 and I have installed it by yum

# Sample Logstash configuration for creating a simple
input {
  jdbc {
    jdbc_connection_string => "jdbc:oracle:thin:@0.0.0.0:1521:DB"
    # The user we wish to execute our statement as
    jdbc_user => "******"
    jdbc_password => "*******"
    # The path to our downloaded jdbc driver
    jdbc_driver_library => "\etc\logstash\conf.d\jdbc\ojdbc7.jar"
    jdbc_driver_class => "Java::oracle.jdbc.driver.OracleDriver"
    # our query
    statement => "select * from test"
  }
}
output {
  stdout { codec => json_lines }
  elasticsearch { }
}

It was expected to insert data into elasticsearch