title: spring-batch read in null int values
body: <p>I have a file reader to read a customer csv file
  If the int fields are empty
  i get error <code>Field error in object 'target' on field 'custPaymentTerm': rejected value []; codes [typeMismatch.target.custPaymentTerm,typeMismatch.custPaymentTerm,typeMismatch.int,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [target.custPaymentTerm,custPaymentTerm]; arguments []; default message [custPaymentTerm]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'int' for property 'custPaymentTerm'; nested exception is java.lang.NumberFormatException: For input string: ""]
  </code></p>
  
  <p>The class to read the file.
  How does spring-batch-job read , handle null int values.</p>
  
  <p>The second line of my csv data file throws the null error !</p>
  
  <pre><code>public static void readCustomers(String pathToFile) throws Exception {  
       System.out.println(" THE path is:"+pathToFile);
       FlatFileItemReader&lt;Customer&gt; reader = new FlatFileItemReader&lt;&gt;();
       reader.setResource(new FileSystemResource(pathToFile));
  
  
       DelimitedLineTokenizer delimitedTokeniser = new DelimitedLineTokenizer();
       delimitedTokeniser.setNames(new String[]{"valueA", "custPaymentTerm","valueC"});
       DefaultLineMapper&lt;Customer&gt; lineMapper = new DefaultLineMapper&lt;Customer&gt;();
       lineMapper.setLineTokenizer(delimitedTokeniser);
       lineMapper.setFieldSetMapper(new BeanWrapperFieldSetMapper&lt;Customer&gt;() {{setTargetType(Customer.class);}});
       reader.setLineMapper(lineMapper);
       reader.setLinesToSkip(1); //do not read the first line of the csv file.
       reader.open(new ExecutionContext());
       Customer store = null;
       List&lt;Customer&gt; stores = new ArrayList&lt;&gt;();
       do {
           store = reader.read();
           if (store != null) {
               System.out.println("######## -------&gt;"+store.getCustPaymentTerm());
               stores.add(store);
           }
       } while (store != null);
  }
  
  public Customer(){
      String valueA;
      int custPaymentTerm;
      String valueC;
  }
  </code></pre>
  
  <p>Data file content</p>
  
  <pre><code>apple,1,cat
  dog,,rat
  </code></pre>