Introduce EIP-methods handle() and bridge()

* Remove generic argument from `GenericEndpointSpec`: it isn't necessary
* Add check for `one-way` flow in case the last component isn't `MessageProducer`

spring-integration-java-dsl/build.gradle

@@ -57,6 +57,8 @@ dependencies {
 	testCompile "org.mockito:mockito-all:$mockitoVersion"
 	testCompile "org.springframework:spring-test:$springVersion"
 
+	testCompile "org.springframework.integration:spring-integration-event:$springIntegrationVersion"
+
 	jacoco group: "org.jacoco", name: "org.jacoco.agent", version: "0.5.6.201201232323", classifier: "runtime"
 }