Improve split() DSL (#8666)

* Introduce a `SplitterSpec` which can accept possible
splitter variants: `expression`, `function`, `ref` etc.
This way we are going to have a complex endpoint configuration
only with a single method argument.
* Use `SplitterSpec` in a newly introduced `splitWith()`
* Deprecate those `split()` methods which use `SplitterEndpointSpec`.
This method are complex enough because of their several arguments
* Refactor some common `MessageHandler` options initialization
into the `ConsumerEndpointSpec.doGet()`
* Disable failing now `MethodInvokingMessageProcessorTests.testCollectionArgument()`:
or Jackson problem, or fresh SF
* Groovy DSL will be fixed in the separate PR:
https://stackoverflow.com/questions/76595843/groovy-selects-a-defaultgroovymethods-split-instead-of-mine-one

src/reference/asciidoc/amqp.adoc

@@ -1396,7 +1396,7 @@ Consider the following integration flow:
 @Bean
 public IntegrationFlow flow(RabbitTemplate template) {
     return IntegrationFlow.from(Gateway.class)
-            .split(s -> s.delimiters(","))
+            .splitWith(s -> s.delimiters(","))
             .<String, String>transform(String::toUpperCase)
             .handle(Amqp.outboundAdapter(template).routingKey("rk"))
             .get();
@@ -1420,7 +1420,7 @@ The following example shows how to use `BoundRabbitChannelAdvice`:
 @Bean
 public IntegrationFlow flow(RabbitTemplate template) {
     return IntegrationFlow.from(Gateway.class)
-            .split(s -> s.delimiters(",")
+            .splitWith(s -> s.delimiters(",")
                     .advice(new BoundRabbitChannelAdvice(template, Duration.ofSeconds(10))))
             .<String, String>transform(String::toUpperCase)
             .handle(Amqp.outboundAdapter(template).routingKey("rk"))

src/reference/asciidoc/dsl.adoc

@@ -491,14 +491,14 @@ To create a splitter, use the `split()` EIP method.
 By default, if the payload is an `Iterable`, an `Iterator`, an `Array`, a `Stream`, or a reactive `Publisher`, the `split()` method outputs each item as an individual message.
 It accepts a lambda, a SpEL expression, or any `AbstractMessageSplitter` implementation.
 Alternatively, you can use it without parameters to provide the `DefaultMessageSplitter`.
-The following example shows how to use the `split()` method by providing a lambda:
+The following example shows how to use the `splitWith()` method by providing a lambda:
 
 [source,java]
 ----
 @Bean
 public IntegrationFlow splitFlow() {
     return IntegrationFlow.from("splitInput")
-              .split(s -> s.applySequence(false).delimiters(","))
+              .splitWith(s -> s.applySequence(false).delimiters(","))
               .channel(MessageChannels.executor(taskExecutor()))
               .get();
 }

src/reference/asciidoc/kafka.adoc

@@ -110,7 +110,7 @@ public ProducerFactory<Integer, String> producerFactory() {
 @Bean
 public IntegrationFlow sendToKafkaFlow() {
     return f -> f
-            .<String>split(p -> Stream.generate(() -> p).limit(101).iterator(), null)
+            .splitWith(s -> s.<String>function(p -> Stream.generate(() -> p).limit(101).iterator()))
             .publishSubscribeChannel(c -> c
                     .subscribe(sf -> sf.handle(
                             kafkaMessageHandler(producerFactory(), TEST_TOPIC1)

src/reference/asciidoc/whats-new.adoc

@@ -30,4 +30,4 @@ See <<./debezium.adoc#debezium, Debezium Support>>  for more information.
 See <<./endpoint.adoc#endpoint-pollingconsumer, Polling Consumer>> for more information.
 
 - Java, Groovy and Kotlin DSLs have now context-specific methods in the `IntegationFlowDefinition` with a single `Consumer` argument to configure an endpoint and its handler with one builder and readable options.
-See, for example, `transformWith()` in <<./dsl.adoc#java-dsl, Java DSL Chapter>>.
+See, for example, `transformWith()`, `splitWith()` in <<./dsl.adoc#java-dsl, Java DSL Chapter>>.