Update docs with new features of v4.1.0.M3

spring-batch-docs/asciidoc/appendix.adoc

@@ -58,7 +58,8 @@
             Spring Data repository implementation.
 |StoredProcedureItemReader|Reads from a database cursor resulting from the
             execution of a database stored procedure. See link:readersAndWriters.html#StoredProcedureItemReader[`StoredProcedureItemReader`]
-|StaxEventItemReader|Reads via StAX. see link:readersAndWriters.html#flatFileItemReader[`FlatFileItemReader`].
+|StaxEventItemReader|Reads via StAX. see link:readersAndWriters.html#StaxEventItemReader[`StaxEventItemReader`].
+|JsonItemReader|Reads items from a Json document. see link:readersAndWriters.html#JsonItemReader[`JsonItemReader`].
 
 |===============
 
@@ -119,5 +120,7 @@
 |StaxEventItemWriter|Uses a `Marshaller` implementation to
             convert each item to XML and then writes it to an XML file using
             StAX.
+|JsonFileItemWriter|Uses a `JsonObjectMarshaller` implementation to
+            convert each item to Json and then writes it to an Json file.
 
 |===============

spring-batch-docs/asciidoc/readersAndWriters.adoc

@@ -1348,6 +1348,25 @@ In the previous example, the `BeanWrapperFieldExtractor` described earlier in th
 chapter is used to turn the name and credit fields within `CustomerCredit` into an object
 array, which is then written out with commas between each field.
 
+It is also possible to use the `FlatFileItemWriterBuilder.DelimitedBuilder` to
+automatically create the `BeanWrapperFieldExtractor` and `DelimitedLineAggregator`
+as shown in the following example:
+
+.Java Configuration
+[source, java, role="javaContent"]
+----
+@Bean
+public FlatFileItemWriter<CustomerCredit> itemWriter(Resource outputResource) throws Exception {
+	return new FlatFileItemWriterBuilder<CustomerCredit>()
+				.name("customerCreditWriter")
+				.resource(outputResource)
+				.delimited()
+				.delimiter(",")
+				.names(new String[] {"name", "credit"})
+				.build();
+}
+----
+
 [[fixedWidthFileWritingExample]]
 ===== Fixed Width File Writing Example
 
@@ -1418,6 +1437,25 @@ The underlying implementation is built using the same
 language. Most details on how to configure a formatter can be found in
 the Javadoc of link:$$https://docs.oracle.com/javase/8/docs/api/java/util/Formatter.html$$[Formatter].
 
+It is also possible to use the `FlatFileItemWriterBuilder.FormattedBuilder` to
+automatically create the `BeanWrapperFieldExtractor` and `FormatterLineAggregator`
+as shown in following example:
+
+.Java Configuration
+[source, java, role="javaContent"]
+----
+@Bean
+public FlatFileItemWriter<CustomerCredit> itemWriter(Resource outputResource) throws Exception {
+	return new FlatFileItemWriterBuilder<CustomerCredit>()
+				.name("customerCreditWriter")
+				.resource(outputResource)
+				.formatted()
+				.format("%-9s%-2.0f")
+				.names(new String[] {"name", "credit"})
+				.build();
+}
+----
+
 [[handlingFileCreation]]
 ===== Handling File Creation
 

spring-batch-docs/asciidoc/whatsnew.adoc

@@ -254,3 +254,69 @@ public BeanValidatingItemProcessor<Person> beanValidatingItemProcessor() throws
 }
 ----
 
+=== JSR-305 support
+
+This release adds support for JSR-305 annotations. It leverages Spring Framework’s
+link:$$https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#null-safety$$[Null-safety]
+annotations and adds them on all public APIs of Spring Batch.
+
+These annotations will not only enforce null-safety when using Spring Batch APIs,
+but also can be used by IDEs to provide useful information related to nullability.
+For example, if a user wants to implement the `ItemReader` interface, any IDE
+supporting JSR-305 annotations will generate something like:
+
+[source, java]
+----
+public class MyItemReader implements ItemReader<String> {
+
+	@Nullable
+	public String read() throws Exception {
+		return null;
+	}
+
+}
+----
+
+The `@Nullable` annotation present on the `read` method makes it clear that the
+contract of this method says it may return `null`. This enforces what is said in its
+Javadoc, that the `read` method should return `null` when the data source is exhausted.
+
+=== `FlatFileItemWriterBuilder` enhancements
+
+Another small feature added in this release is a simplification of the configuration
+for the writing of a flat file. Specifically, these updates simplify the configuration
+of both a delimited and fixed width file. Below is an example of before and after the change.
+
+[source, java]
+----
+// Before
+@Bean
+public FlatFileItemWriter<Item> itemWriter(Resource resource) {
+	BeanWrapperFieldExtractor<Item> fieldExtractor =
+            new BeanWrapperFieldExtractor<Item>();
+	fieldExtractor.setNames(new String[] {"field1", "field2", "field3"});
+	fieldExtractor.afterPropertiesSet();
+
+	DelimitedLineAggregator aggregator = new DelimitedLineAggregator();
+	aggregator.setFieldExtractor(fieldExtractor);
+	aggregator.setDelimiter(";");
+
+	return new FlatFileItemWriterBuilder<Item>()
+			.name("itemWriter")
+			.resource(resource)
+			.lineAggregator(aggregator)
+			.build();
+}
+
+// After
+@Bean
+public FlatFileItemWriter<Item> itemWriter(Resource resource) {
+	return new FlatFileItemWriterBuilder<Item>()
+			.name("itemWriter")
+			.resource(resource)
+			.delimited()
+			.delimiter(";")
+			.names(new String[] {"field1", "field2", "field3"})
+			.build();
+}
+----