Remove deprecations from previous versions

* Remove Boon dependency and its usage
* Remove overloaded methods from the `IntegrationFlowDefinition`
- we can simply rely now on the super class
* Remove (or rework) deprecated entities in the docs
* Fix tests for removed deprecated APIs
* Rework affected tests to JUnit 5

src/reference/asciidoc/dsl.adoc

@@ -968,7 +968,7 @@ public class MyFlowAdapter extends IntegrationFlowAdapter {
 
     @Override
     protected IntegrationFlowDefinition<?> buildFlow() {
-        return from(this, "messageSource",
+        return from(this::messageSource,
                       e -> e.poller(p -> p.trigger(this::nextExecutionTime)))
                  .split(this)
                  .transform(this)
@@ -1174,7 +1174,7 @@ By default a `GatewayProxyFactoryBean` gets a conventional bean name, such as `[
 You can change that ID by using the `@MessagingGateway.name()` attribute or the overloaded `IntegrationFlows.from(Class<?> serviceInterface, Consumer<GatewayProxySpec> endpointConfigurer)` factory method.
 Also all the attributes from the `@MessagingGateway` annotation on the interface are applied to the target `GatewayProxyFactoryBean`.
 When annotation configuration is not applicable, the `Consumer<GatewayProxySpec>` variant can be used for providing appropriate option for the target proxy.
-This DSL method is available starting with version 5.2; the method `IntegrationFlows.from(Class<?> serviceInterface, String beanName)` is deprecated in favor of `GatewayProxySpec.beanName()` option.
+This DSL method is available starting with version 5.2.
 
 With Java 8, you can even create an integration gateway with the `java.util.function` interfaces, as the following example shows:
 

src/reference/asciidoc/testing.adoc

@@ -70,16 +70,16 @@ See the https://docs.spring.io/spring-integration/api/org/springframework/integr
 
 ==== Using the `SocketUtils` Class
 
-The https://docs.spring.io/spring-integration/api/org/springframework/integration/test/util/SocketUtils.html[`SocketUtils` class] provides several methods that select one or more random ports for exposing server-side components without conflicts, as the following example shows:
+The https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/util/SocketUtils.html[`SocketUtils` class] provides several methods that select one or more random ports for exposing server-side components without conflicts, as the following example shows:
 
 ====
 [source,xml]
 ----
-<bean id="socketUtils" class="org.springframework.integration.test.util.SocketUtils" />
+<bean id="socketUtils" class="org.springframework.util.SocketUtils" />
 
 <int-syslog:inbound-channel-adapter id="syslog"
             channel="sysLogs"
-            port="#{socketUtils.findAvailableUdpSocket(1514)}" />
+            port="#{socketUtils.findAvailableUdpPort(1514)}" />
 
 <int:channel id="sysLogs">
     <int:queue/>

src/reference/asciidoc/transformer.adoc

@@ -359,14 +359,10 @@ To avoid unexpected issues with JSON mapping features when you use annotations,
 
 [source,java]
 ----
-@org.codehaus.jackson.annotate.JsonIgnoreProperties(ignoreUnknown=true)
 @com.fasterxml.jackson.annotation.JsonIgnoreProperties(ignoreUnknown=true)
-@org.boon.json.annotations.JsonIgnoreProperties("thing1")
 public class Thing1 {
 
-        @org.codehaus.jackson.annotate.JsonProperty("thing1Thing2")
         @com.fasterxml.jackson.annotation.JsonProperty("thing1Thing2")
-        @org.boon.json.annotations.JsonProperty("thing1Thing2")
         public Object thing2;
 
 }