Fix Groovy DSL for new splitter style (#8669)

* Fix Groovy DSL for new splitter style

* Introduce a new `GroovyIntegrationFlowDefinition.splitWith()`
to avoid clashing with existing method
* Deprecate all other `split()` variants, but left one without arguments
for a default splitting options
* Fix doc for new splitter style

* * Fix tab indentations in `groovy-dsl.adoc`

src/reference/asciidoc/groovy-dsl.adoc

@@ -89,8 +89,15 @@ functionFlow() {
 		            transformer { it.toUpperCase() }
                     expectedType String
                 }
-                split Message<?>, { it.payload }
-                split Object, { it }, { id 'splitterEndpoint' }
+                splitWith {
+                    expectedType Message<?>
+                    function { it.payload }
+                }
+                splitWith {
+                    expectedType Object
+                    id 'splitterEndpoint'
+                    function { it }
+                }
                 resequence()
                 aggregate {
                     id 'aggregator'

src/reference/asciidoc/splitter.adoc

@@ -97,7 +97,10 @@ fun someFlow() =
 @Bean
 someFlow() {
     integrationFlow {
-        split Message<?>, { it.payload }
+        splitWith {
+		    expectedType Message<?>
+		    function { it.payload }
+        }
     }
 }
 ----

src/reference/asciidoc/zip.adoc

@@ -229,8 +229,12 @@ fun unzipFlow(executor: Executor) =
 unzipFlow(Executor executor) {
     integrationFlow 'unzipChannel',
             {
-                transform new UnZipTransformer()
-                split new UnZipResultSplitter()
+                transformWith {
+                    ref new UnZipTransformer()
+                }
+                splitWith {
+                    ref new UnZipResultSplitter()
+                }
                 channel { executor 'entriesChannel', executor }
             }
 }