title: Selma - Bad custom field to field mapping
body: <p>I have a project that uses Mapstrcut, i want to replace it by Selma, so in the below example i mapped AttachmentRequest to Attachment</p>
  <pre><code>public class Attachment {
      private SocialReason socialReason;
      public SocialReason getSocialReason() { return socialReason; }
      public Attachment socialReason(SocialReason socialReason) { this.socialReason = socialReason; return this; }
  }
  
  public class SocialReason {
      private String value;
      public String getValue() { return value; }
      public SocialReason value(String value) { this.value = value; return this; }
  }
  
  public class AttachmentRequest {
      private String socialReason;
      public String getSocialReason() { return socialReason; }
      public AttachmentRequest socialReason(String socialReason) { this.socialReason = socialReason; return this; }
  }
  </code></pre>
  <p>I tried with the bellow code, but i have this error</p>
  <blockquote>
  <p>Bad custom field to field mapping: field out.getSocialReason().value
  from destination bean Attachment has no setter !
  --&gt;  Fix @Field({&quot;socialreason&quot;,&quot;socialreason.value&quot;})</p>
  </blockquote>
  <pre><code>@Mapper(withIgnoreMissing = IgnoreMissing.ALL)
  public interface AttachmentCommandMapper {
      @Maps(withCustomFields = { @Field({ &quot;socialReason&quot;, &quot;socialReason.value&quot; }) })
      Attachment attachmentRequestToAttachment(AttachmentRequest attachmentRequest);
  }
  </code></pre>
  <p>Is setters required in the class for the mapping in Selma, because in mapstruct doesn't require setters.</p>