title: How to parse fixed length records using beanIO?
body: <p>I'm using <code>beanio</code> to parse a fixed length content (single string line). I want to use annotation based configuration, but it does not work.</p>
  
  <p>What might wrong with the following code?</p>
  
  <pre><code>        StreamBuilder builder = new StreamBuilder("s1").addRecord(MyRecord.class);
          StreamFactory factory = StreamFactory.newInstance();
          factory.define(builder);
  
          Unmarshaller unmarshaller = factory.createUnmarshaller("s1");
          unmarshaller.unmarshal("123ASD");
  
  @Record(minOccurs = 1, maxOccurs = 1)
  public class MyRecord {
  
      @Field(at = 1, length = 3, minOccurs = 1)
      private String number;
  
      @Field(at = 4, length = 3, minOccurs = 1)   
      private String text;
  }
  
  
  org.beanio.InvalidRecordException: Invalid 'myRecord' record
   ==&gt; Invalid 'number':  Expected minimum 1 occurrences
   ==&gt; Invalid 'text':  Expected minimum 1 occurrences
      at org.beanio.internal.parser.UnmarshallingContext.validate(UnmarshallingContext.java:200)
      at org.beanio.internal.parser.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:204)
      at org.beanio.internal.parser.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:89)
  </code></pre>