Fix java-dsl-gateway double usage in Docs

Author: artembilan

src/reference/asciidoc/dsl.adoc

@@ -1257,7 +1257,7 @@ In this case, the message handler for the first flow can be referenced with bean
 
 NOTE: An `id` attribute is required when you usE `useFlowIdAsPrefix()`.
 
-[[java-dsl-gateway]]
+[[integration-flow-as-gateway]]
 === `IntegrationFlow` as a Gateway
 
 The `IntegrationFlow` can start from the service interface that provides a `GatewayProxyFactoryBean` component, as the following example shows:

src/reference/asciidoc/gateway.adoc

@@ -867,4 +867,4 @@ At that time, the calling thread starts waiting for the reply.
 If the flow was completely synchronous, the reply is immediately available.
 For asynchronous flows, the thread waits for up to this time.
 
-See <<./dsl.adoc#java-dsl-gateway,`IntegrationFlow` as Gateway>> in the Java DSL chapter for options to define gateways through `IntegrationFlows`.
+See <<./dsl.adoc#integration-flow-as-gateway,`IntegrationFlow` as Gateway>> in the Java DSL chapter for options to define gateways through `IntegrationFlows`.

src/reference/asciidoc/rsocket.adoc

@@ -343,4 +343,4 @@ public IntegrationFlow rsocketUpperCaseRequestFlow(ClientRSocketConnector client
 ----
 ====
 
-See <<./dsl.adoc#java-dsl-gateway,`IntegrationFlow` as a Gateway>> for more information how to use a mentioned `Function` interface in the beginning of the flow above.
+See <<./dsl.adoc#integration-flow-as-gateway,`IntegrationFlow` as a Gateway>> for more information how to use a mentioned `Function` interface in the beginning of the flow above.