title: spring integration: sftp inbound-channel-adapter The authenticity of host 'x.x.x.x' can't be established
body: <p>I tried to download files using the following code:</p>
  
  <pre><code>&lt;int-sftp:inbound-channel-adapter id="sftpInbondAdapter"
      auto-startup="true" channel="receiveChannel" session-factory="sftpSessionFactory"
      local-directory="file:${directory.files.local}" remote-directory="${directory.files.remote}"
      auto-create-local-directory="true" delete-remote-files="true"
      filename-pattern="*.txt"&gt;
      &lt;int:poller fixed-delay="${sftp.interval.request}"
  max-messages-per-poll="-1" error-channel="sftp.in.error.channel" /&gt;
  &lt;/int-sftp:inbound-channel-adapter&gt;
  
  &lt;bean id="defaultSftpSessionFactory"
      class="org.springframework.integration.sftp.session.DefaultSftpSessionFactory"&gt;
  
      &lt;property name="host" value="${sftp.host}" /&gt;
      &lt;property name="port" value="${sftp.port}" /&gt;
      &lt;property name="user" value="${user}" /&gt;
      &lt;property name="password" value="${password}" /&gt;
      &lt;property name="allowUnknownKeys" value="true" /&gt;
  &lt;/bean&gt;
  </code></pre>
  
  <p>I'm sure that the user is authorized because i tried it with shell:
  sftp user@x.x.x.x
  then i write the password and the download succeed with "get".</p>
  
  <p>but i can't download files, the error is:</p>
  
  <p>DEBUG LOG:</p>
  
  <pre><code>        jsch:52 - Authentications that can continue: gssapi-with-mic,publickey,keyboard-interactive,password
  2016-02-02 07:54:04 INFO  jsch:52 - Next authentication method: gssapi-with-mic
  2016-02-02 07:54:04 INFO  jsch:52 - Authentications that can continue: publickey,keyboard-interactive,password
  2016-02-02 07:54:04 INFO  jsch:52 - Next authentication method: publickey
  2016-02-02 07:54:04 INFO  jsch:52 - Authentications that can continue: password
  2016-02-02 07:54:04 INFO  jsch:52 - Next authentication method: password
  2016-02-02 07:54:04 INFO  jsch:52 - Authentication succeeded (password).
  2016-02-02 07:54:05 DEBUG SimplePool:190 - Obtained new org.springframework.integration.sftp.session.SftpSession@39c9c99a.
  2016-02-02 07:54:05 DEBUG CachingSessionFactory:187 - Releasing Session org.springframework.integration.sftp.session.SftpSession@39c9c99a back to the pool.
  2016-02-02 07:54:05 INFO  jsch:52 - Disconnecting from x.x.x.x port 22
  </code></pre>